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Video File Format Specification
Version 10
Copyright © 2008 Adobe Systems Incorporated. All rights reserved. This manual may not be copied, photocopied, reproduced, translated, or converted to any electronic ormachine-readable form in whole or in part without writtenapproval from AdobeSystems Incorporated. Notwithstanding the foregoing, apersonobtaining an electronic version of this manualfrom Adobe may print out one copy of this manual provided that nopart of this manual may beprinted out, reproduced, distributed, resold, ortransmitted for any other purposes, including, without limitation, commercial purposes, such as selling copies of thisdocumentation or providing paid-for support services.
Trademarks
Adobe, ActionScript,Flash, Flash Media Server, XMP, and Flash Player are either registered trademarks or trademarks of Adobe Systems Incorporated and may be registered inthe United States orin other jurisdictions including internationally. Other product names, logos, designs, titles,words, or phrases mentioned within this publication may be trademarks, service marks, or trade names of Adobe SystemsIncorporated or other entities andmay be registered incertain jurisdictions includinginternationally. No right or license is grantedto any Adobe trademark.
Third–Party Information
This guide contains linksto third-party websites that are not under the control of Adobe SystemsIncorporated, and AdobeSystems Incorporated is not responsible for the content on any linked site. If you access a third-party website mentioned inthis guide, then you do so at your own risk. Adobe Systems Incorporated provides these links only as a convenience, and the inclusion of the link does not imply that Adobe Systems Incorporated endorses or accepts any responsibility for the content on those third- party sites. No right, license or interest isgranted in any third party technology referenced inthis guide.
NOTICE: THIS PUBLICATION AND THE INFORMATION HEREIN ISFURNISHED “AS IS”, IS SUBJECT TOCHANGE WITHOUT NOTICE, AND SHOULDNOT BE CONSTRUED AS A COMMITMENT BY ADOBESYSTEMS INCORPORATED. ADOBE SYSTEMS INCORPORATED ASSUMES NO RESPONSIBILITY ORLIABILITY FOR ANY ERRORS OR INACCURACIES, MAKES NO WARRANTY OF ANY KIND (EXPRESS,IMPLIED, OR STATUTORY) WITH RESPECT TO THIS PUBLICATION, AND EXPRESSLY DISCLAIMS ANY AND ALL WARRANTIES OFMERCHANTABILITY, FITNESSFOR PARTICULAR PURPOSES, AND NONINFRINGEMENT OFTHIRD PARTY RIGHTS.
Adobe Systems Incorporated
Published November 2008
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The FLV file format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The F4V file format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
What’s new in Video File Format 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Speex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
XMP Metadata .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 1: The FLV File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
The FLV header .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The FLV file body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
FLV tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Audiotags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
AUDIODATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
AACAUDIODATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Videotags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
VIDEODATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
AVCVIDEOPACKET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Data tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 onMetaData . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 2: The F4V File Format. . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The F4V box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 ftyp box .. . .. . . . . . . .. . .. . .. . . . . . . .. . .. . .. . . . . . . .. . .. . .. . . . . . . .. 18moovbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 mvhd box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 trak box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 udta box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 meta box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 mdia box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 minf box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 stblbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 tkhd box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 mdhd box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 stsd box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
i
stsc box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 stts box. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 ctts box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 stco and co64 boxes .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 stss box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 stsz box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 chpl box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 pdin box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 mdat box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Required structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Supported media types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Unsupported boxes .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Chapter 3: F4V Metadata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Tag box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 ilst box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Imagemetadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Text metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 styl box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 hlit box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 hclr box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 krok box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 dlay box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 drpo box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 drpt box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 href box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 tbox box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 blnk box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 twrp box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
XMP Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
uuid box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
ii Contents
Introduction
This document provides technical format information for the video file formats supported by
Adobe® Flash® Player software—FLV and F4V.
Adobe seriously considersall feedback to the video file format specification. E-mail any unclear or potentially erroneous information withinthe specification to Adobe at flashformat@adobe.com. All such email submissions shall besubject to the SubmittedMaterials guidelines inthe Terms of Use at www.adobe.com/misc/copyright.html.
The FLV file format
Starting with SWF files published for Flash Player 6,Flash Player can exchange audio, video, and data over RTMP connections with the Adobe Flash Media Server™. One way to feed datato Flash Media Server (and thus onto Flash Player clients) is from files inthe FLV file format.Starting with SWF files published for Flash Player 7,Flash Player can also play FLV files directly with MIME type video/x-flv.
An FLV file encodes synchronized audio and video streams. The audio and video data within
FLV files are encoded inthe same way as audio and video within SWF files.
This document describes FLV version 1.For more information ontheFLV format, see
Chapter 1, “The FLV File Format,” onpage 3.
The F4V file format
Starting with SWF files published for Flash Player 9Update 3 (9,0,115,0), Flash Player canplay F4V files. The F4V format is based onthe format specified by ISO/IEC 14496–12: ISO base media file format. For more information on the F4V format, see Chapter 2, “The F4V File Format,” onpage 17.
A large part of the F4V format involves metadata. For more information onF4Vmetadata, see Chapter 3, “F4V Metadata,” onpage35.
What’s new in Video File Format 10
The following features are new in theFlash video file format specifications (both FLV and
F4V) corresponding to Flash Player 10.
Speex
Flash Player 10 supports the open source Speex audio codec. Speex data can serve as the audio stream in an FLV file. See “AUDIODATA” onpage 6.
XMP Metadata
The F4V file format supports a box type called ‘uuid‘ which canstore data formatted in Adobe’s Extensible Metadata Platform (XMP™) and present it to a SWF file via ActionScript®. See “XMP Metadata” onpage 43.
CHAPTER 1
|
The FLV File Format
Each tag type in an FLV file constitutes asingle stream. There can be no more than one audioand one video stream, synchronized together, in an FLV file. AnFLV file cannot define multiple independent streams of a single type.
Unlike SWF files, FLV files store multibyte integers inbig–endian byte order. For example, as a UI16 in SWF file format, the byte sequence that represents the number 300 (0x12C) is
0x2C 0x01; as a UI16 in FLV file format, the byte sequence that represents thenumber 300 is
0x01 0x2C. Also, FLV files use a3–byte integer type that is not used inSWF files: a UI24 represents anunsigned 24-bit integer.
The FLV header
All FLV files begin with the following header:
|
FLV header
Field
|
Type
|
Comment
|
|
Signature
|
UI8
|
Signature byte always ‘F’ (0x46)
|
|
Signature
|
UI8
|
Signature byte always ‘L’ (0x4C)
|
|
Signature
|
UI8
|
Signature byte always ‘V’ (0x56)
|
|
Version
|
UI8
|
File version (for example, 0x01 for FLV
version 1)
|
|
TypeFlagsReserved
|
UB[5]
|
Must be 0
|
|
TypeFlagsAudio
|
UB[1]
|
Audio tags are present
|
|
TypeFlagsReserved
|
UB[1]
|
Must be 0
|
|
TypeFlagsVideo
|
UB[1]
|
Video tags are present
|
|
DataOffset
|
UI32
|
Offset in bytes from start of file to start of body (that is, size of header)
|
The DataOffset field usuallyhas a value of9 for FLV version 1. This field is present toaccommodate largerheaders in future versions.
The FLV file body
After the FLV header, the remainder of an FLV file consists of alternating back-pointers and tags. They interleave as shown in the following table:
|
FLV file body
Field
|
Type
|
Comment
|
|
PreviousTagSize0
|
UI32
|
Always 0
|
|
Tag1
|
FLVTAG
|
First tag
|
|
PreviousTagSize1
|
UI32
|
Size of previous tag, including its header. For FLV version 1, this value is 11 plus the DataSize of the previous tag.
|
|
Tag2
|
FLVTAG
|
Second tag
|
|
...
|
|
|
|
FLV file body
Field
|
Type
|
Comment
|
|
PreviousTagSizeN-1
TagN PreviousTagSizeN
|
UI32
FLVTAG UI32
|
Size of second–to–last tag
Last tag
Size of last tag
|
FLV tags
FLV tags have the following format:
|
FLVTAG
Field
|
Type
|
Comment
|
|
TagType
|
UI8
|
Type of this tag. Values are:
8: audio
9: video
18: script data
all others: reserved
|
|
DataSize
|
UI24
|
Length of the data in the Data field
|
|
Timestamp
|
UI24
|
Time in milliseconds at which the data in this tag applies. This value is relative to the first tag in the FLV file, which always has a timestamp of 0.
|
|
TimestampExtended
|
UI8
|
Extension of the Timestamp field to form a SI32 value. This field represents the upper 8 bits, while the previous Timestamp field represents the lower 24 bits of the time in milliseconds.
|
|
StreamID
|
UI24
|
Always 0
|
|
Data
|
If TagType == 8
AUDIODATA If TagType == 9
VIDEODATA
If TagType == 18
|
Body of the tag
|
SCRIPTDATAOBJECT
In playback, thetime sequencing ofFLV tags depends onthe FLV timestamps only. Any timingmechanisms built into the payload data formatare ignored.
Audio tags
Audio tags are similar to the DefineSound tag inthe SWF file format. Their payload data isidentical except for the additional Nellymoser 8-kHz format,whichis not permittedin SWF. (For information on the SWF file format, see the SWF File Format Specification at www.adobe.com/go/swf_file_format.)
AUDIODATA
|
AUDIODATA
Field
|
Type
|
Comment
|
|
SoundFormat
(see notes following
|
UB[4]
0 = Linear PCM, platform endian
1 = ADPCM
|
Format of SoundData
Formats 7, 8, 14, and 15 are
|
|
table)
|
2 = MP3
3 = Linear PCM, little endian
4 = Nellymoser 16-kHz mono
|
reserved for internal use
AAC is supported in Flash
|
|
|
5 = Nellymoser 8-kHz mono
6 = Nellymoser
7 = G.711 A-law logarithmic PCM
|
Player 9,0,115,0 and higher.
Speex is supported in Flash
|
|
|
8 = G.711 mu-law logarithmic PCM
9 = reserved
10 = AAC
11 = Speex
14 = MP3 8-Khz
15 = Device-specific sound
|
Player 10 and higher.
|
|
SoundRate
|
UB[2]
0 = 5.5-kHz
1 = 11-kHz
2 = 22-kHz
3 = 44-kHz
|
Sampling rate
For AAC: always 3
|
|
SoundSize
|
UB[1]
0 = snd8Bit
1 = snd16Bit
|
Size of each sample. This parameter only pertains to uncompressed formats. Compressed formats always decode to 16 bits internally.
0 = snd8Bit
1 = snd16Bit
|
|
AUDIODATA
Field
|
Type
|
Comment
|
|
SoundType
|
UB[1]
0 = sndMono
1 = sndStereo
|
Mono or stereo sound
For Nellymoser: always 0
For AAC: always 1
|
|
SoundData
|
UI8[size of sound data]
|
if SoundFormat == 10
AACAUDIODATA
|
else
Sound data—varies by format
Format 3, linear PCM, stores raw PCM samples. If the data is 8-bit, the samples are unsigned bytes. Ifthe data is 16-bit, the samples are stored as little endian, signed numbers. Ifthe data is stereo, left and right samples are stored interleaved: left –right – left – right – and so on.
Format 0PCM is the same as format 3 PCM,except that format 0 stores 16–bit PCM samples inthe endian order of the platformon which the file was created. For this reason, format 0 is not recommended for use.
Nellymoser 8-kHz and 16-kHz are special cases— 8- and 16-kHz sampling rates are not supported in other formats, and the SoundRate bits can’t represent this value. WhenNellymoser 8-kHz or Nellymoser 16-kHz is specified inSoundFormat, theSoundRate and SoundType fields are ignored. For other Nellymoser samplingrates, specify the normal Nellymoser SoundFormat and use the SoundRate and SoundType fields as usual.
If the SoundFormat indicates AAC, the SoundType should be set to 1 (stereo) and the SoundRate should be set to 3 (44 kHz). However, this does not mean that AAC audio in FLV is always stereo, 44kHz data. Instead, the Flash Player ignores these values and extracts the channel and sample rate data is encoded in the AAC bitstream.
For information regarding Speex capabilities and limitationswhen stored in a SWF file, seethe SWF File Format Specification.
AACAUDIODATA
The AAC format is supported in Flash Player 9,0,115,0 and higher.
|
AACAUDIODATA
Field
|
Type
|
Comment
|
|
AACPacketType
|
UI8
|
0: AAC sequence header
1: AAC raw
|
|
Data
|
UI8[n]
|
if AACPacketType == 0
AudioSpecificConfig
|
else if AACPacketType == 1
Raw AAC frame data
The AudioSpecificConfig is explainedin ISO 14496–3. Note that it is not the same as the contents of the esds box from an MP4/F4V file. This structure is more deeply embedded.
Video tags
Video tags aresimilar to the VideoFrame tag in the SWF file format, and their payload data is identical. (For information on the SWF file format, see the SWF File Format Specification atwww.adobe.com/go/swf_file_format.)
VIDEODATA
|
VIDEODATA
Field
|
Type
|
Comment
|
|
FrameType
|
UB[4]
|
1: keyframe (for AVC, a seekable frame)
2: inter frame (for AVC, a non- seekable frame)
3: disposable inter frame (H.263 only)
4: generated keyframe (reserved for server use only)
5: video info/command frame
|
|
CodecID
|
UB[4]
|
1: JPEG (currently unused)
2: Sorenson H.263
3: Screen video
4: On2 VP6
5: On2 VP6 with alpha channel
6: Screen video version 2
7: AVC
|
|
VideoData
|
If CodecID == 2
H263VIDEOPACKET
|
Video frame payload or UI8 (see note following table)
|
If CodecID == 3
SCREENVIDEOPACKET If CodecID == 4
VP6FLVVIDEOPACKET If CodecID == 5
VP6FLVALPHAVIDEOPACKET If CodecID == 6
SCREENV2VIDEOPACKET
if CodecID == 7
AVCVIDEOPACKET
If FrameType = 5, instead of a video payload, the message stream contains aUI8 with the following meaning:
■ 0 = Start of client-side seeking video frame sequence
■ 1 = End of client-sideseeking video frame sequence
AVCVIDEOPACKET
An AVCVIDEOPACKET carries apayload of AVC video data.
|
AVCVIDEOPACKET
Field
|
Type
|
Comment
|
|
AVCPacketType
|
UI8
|
0: AVC sequence header
1: AVC NALU
2: AVC end of sequence (lower level NALU
sequence ender is not required or supported)
|
|
CompositionTime
|
SI24
|
if AVCPacketType == 1
|
Composition time offset
else
0
Data UI8[n] if AVCPacketType == 0
AVCDecoderConfigurationRecordelse if AVCPacketType== 1
One or more NALUs (can be individual slices per FLV packets; that is, full framesarenot strictly required)
else ifAVCPacketType == 2
Empty
See ISO 14496-12, 8.15.3 for an explanation ofcomposition times. The offset in an FLV fileis always inmilliseconds.
See ISO 14496-15, 5.2.4.1 for the description of AVCDecoderConfigurationRecord. Thiscontains the same information that would be stored inan avcC box in an MP4/FLV file.
Data tags
Data tags encapsulate single-method invocation, which is usually called ona NetStream object inFlash Player. Data tags are formed from a method name and a set of arguments.
|
SCRIPTDATA
Field
|
Type
|
Comment
|
|
Objects
|
SCRIPTDATAOBJECT[]
|
Arbitrary number of
SCRIPTDATAOBJECT structures
|
|
End
|
UI24
|
Always 9, also known as a
SCRIPTDATAOBJECTEND
|
SCRIPTDATAOBJECT and SCRIPTDATAOBJECTEND
A SCRIPTDATAOBJECT record defines objectdata inActionScript. Lists of SCRIPTDATAOBJECT records are terminated by using the SCRIPTDATAOBJECTEND tag.
|
SCRIPTDATAOBJECT
Field
|
Type
|
Comment
|
|
ObjectName
ObjectData
|
SCRIPTDATASTRING
SCRIPTDATAVALUE
|
Name of the object
Data of the object
|
|
SCRIPTDATAOBJECTEND
| ||
|
Field
|
Type
|
Comment
|
|
ObjectEndMarker2
|
UI24
|
Always 9
|
SCRIPTDATASTRING and SCRIPTDATALONGSTRING
The SCRIPTDATASTRING and SCRIPTDATALONGSTRING records are used todefinestrings for data tags.
The SCRIPTDATALONGSTRING record can be used to specify strings larger than 65535 characters.
|
SCRIPTDATASTRING
Field
|
Type
|
Comment
|
|
StringLength
StringData
|
UI16
STRING
|
String length in bytes
String data
|
|
SCRIPTDATALONGSTRING
| ||
|
Field
|
Type
|
Comment
|
|
StringLength
StringData
|
UI32
STRING
|
String length in bytes
String data
|
SCRIPTDATAVALUE
A SCRIPTDATAVALUE record represents an abstract definition ofan ActionScript value or object. It can contain a list of values, objects, variables, orarrays.
SCRIPTDATAVALUE
Field Type Comment
Type
(see notes following table)
UI8 Type ofthe variable:
0 = Number type
1 = Boolean type
2 = String type
3 = Object type
4 = MovieClip type
5 = Null type
6 = Undefined type
7 = Reference type
8 = ECMA array type
10 = Strict array type
11 = Date type
12 = Long stringtype
ECMAArrayLength If Type = 8, UI32 Approximate number of fields of ECMA array
SCRIPTDATAVALUE
Field Type Comment
ScriptDataValue If Type == 0
DOUBLE If Type == 1
UI8
If Type == 2
SCRIPTDATASTRING If Type == 3
SCRIPTDATAOBJECT[n]If Type == 4
SCRIPTDATASTRING
defining
the MovieClip path
If Type == 7
UI16
If Type == 8
SCRIPTDATAVARIABLE[EC MAArrayLength]
If Type == 10
SCRIPTDATAVARIABLE[n] If Type == 11
SCRIPTDATADATE If Type == 12
SCRIPTDATALONGSTRING
Script data values
ScriptDataValueTerminator If Type == 3
SCRIPTDATAOBJECTENDIf Type == 8
SCRIPTDATAVARIABLEEND
Terminators for Object and
Strict array lists
If Type = 8 (ECMA array type), the ECMAArrayLength provides a hint to the software about how many items might be in the array. The array continues untilSCRIPTDATAVARIABLEEND appears.
If Type = 10 (strictarray type), the array begins with a UI32 type and contains that exact number of items. Thearray does notterminate with a SCRIPTDATAVARIABLEEND tag.
SCRIPTDATAVARIABLE and
SCRIPTDATAVARIABLEEND
A SCRIPTDATAVARIABLE record defines variable data in ActionScript. Lists of SCRIPTDATAVARIABLE records areterminated by using the SCRIPTDATAVARIABLEEND tag.
SCRIPTDATAVARIABLE
|
Field
|
Type
|
Comment
| |
|
VariableName
VariableData
|
SCRIPTDATASTRING
SCRIPTDATAVALUE
|
Name of the variable
Data of the variable
| |
|
SCRIPTDATAVARIABLEEND
| |||
|
Field
|
Type
|
Comment
|
|
|
VariableEndMarker1
|
UI24
|
Always 9
|
|
SCRIPTDATADATE
A SCRIPTDATADATE record definesa particular date and time.
|
SCRIPTDATADATE
Field
|
Type
|
Comment
|
|
DateTime
|
DOUBLE
|
Number of milliseconds since Jan 1, 1970
UTC.
|
|
LocalDateTimeOffset
|
SI16
|
Local time offset in minutes from UTC. For time zones located west of Greenwich, UK, this value is a negative number. Time zones east of Greenwich, UK, are positive.
|
onMetaData
An FLV file can contain metadata with an “onMetaData” marker. Various stream properties are available to a running ActionScriptprogram via the NetStream.onMetaData property. The availableproperties differ dependingon the software used. Common propertiesinclude:
■ duration: a DOUBLE indicating the totalduration of the file in seconds
■ width: a DOUBLE indicating the width of the video inpixels
■ height: a DOUBLE indicating the height of the video inpixels
■ videodatarate: a DOUBLE indicating thevideo bit rate in kilobits per second
■ framerate: a DOUBLE indicating the number of frames per second
■ videocodecid: a DOUBLEindicating the video codec ID used in the file (see “Video tags” onpage 8for available CodecID values)
■ audiosamplerate: a DOUBLE indicating the frequency at which the audiostream is replayed
■ audiosamplesize: a DOUBLE indicating theresolution ofa single audio sample
■ stereo: a BOOL indicating whether the data is stereo
■ audiocodecid: a DOUBLEindicating the audio codec IDused in the file (see “Audio tags” onpage 6for available SoundFormat values)
■ filesize: a DOUBLE indicating the total size ofthe file in bytes
16 The FLV File Format
CHAPTER 2
|
The F4V File Format
Flash Player Update 3 (9,0,115,0) and higher can play F4V files. The F4V format is based on the format specified byISO/IEC 14496–12: ISO base media file format.
Unlike SWF files, F4V files store multibyte integers in big-endianbyte order. For example, asa UI16 in SWF file format, the byte sequence that represents the number 300 (0x12C) is
0x2C 0x01; as aUI16 in F4V file format, the byte sequence that represents the number 300 is
0x01 0x2C.
This chapter discusses all aspectsof the F4V formatexcept metadata. For information on metadata, see Chapter 3, “F4V Metadata,” onpage 35.
The F4V box
The fundamental building block of an F4V file is abox which has the following BOX format:
|
F4V box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
A consistent header that all boxes have
|
|
Payload
|
UI8[]
|
A number of bytes, the length of which is defined by the BOXHEADER
|
|
Each box structure begins with a BOXHEADER structure:
| ||
|
BOXHEADER
|
|
|
|
Field
|
Type
|
Comment
|
|
TotalSize
|
UI32
|
The total size of the box in bytes, including this header
|
|
BoxType
|
UI32
|
The type of atom
|
|
ExtendedSize
|
If TotalSize equals 1
UI64
|
The total 64-bit length of the box in bytes, including this header
|
Many boxes are wellunder 4 gigabytes in length and can store their size in the TotalSize field. The format also supports very large boxes by setting the 32-bit TotalSize field to1 and storing a 64–bit size inExtendedSize.
Each box is identified with a 32-bit type.For most boxes, this 32-bit type doubles as ahuman–readablefour-character ASCII code or FourCC, such as ‘moov’ (0x6D6F6F76) and
‘mdat’ (0x6D646174).
The box payload immediatelyfollows the box header. Thesize ofthe payload in bytes is equal to the total size of the box minuseither 8 bytes or16 bytes, depending on the size ofthe header.
For more information, see section 4.2 of ISO/IEC 14496–12.
ftyp box
The F4V formatis based on the ISO MP4 format, which inturn is based onthe Apple QuickTime container format. The subsets ofthe format support different features. The ftyp boxhelps identify the features that a program must support to play a particular file.
Flash Player does not enforce anyrestrictionswith respect toftyp boxes. The program tries toplay any file it is given, within the restrictions of the codec types it supports.
|
ftyp box
Field
|
Type
|
Comments
|
|
Header
|
BOXHEADER
|
BoxType = ‘ftyp’ (0x66747970)
|
|
MajorBrand
|
UI32
|
The primary brand identifier
|
|
MinorVersion
|
UI32
|
The secondary brand identifier
|
|
CompatibleBrands
|
UI32[]
|
Arbitrary number of compatible brands, until the end of the box
|
For more information, see section 4.3 of ISO/IEC 14496–12.
moov box
An F4V file must containone and only one moov box. Themoov box is effectively the“header” ofan F4V file. The moov box itselfcontains one or more other boxes, which in turn contain other boxes which define the structure of the F4V data.
|
moov box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘moov’ (0x6D6F6F76)
|
|
Boxes
|
BOX[]
|
Many other boxes which define the structure
|
For more information, see section 8.1 of ISO/IEC 14496–12.
mvhd box
An F4V file must containone and only one mvhd box. The mvhd box is contained within a moov box and defines playback information that applies to the entire F4V file.
|
mvhd box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘mvhd’ (0x6D766864)
|
|
Version
|
UI8
|
Either 0 or 1
|
|
Flags
|
UI24
|
Reserved, set to 0
|
|
CreationTime
|
if Version == 0
SI32
if Version == 1
|
The creation time of the F4V file, expressed as seconds elapsed since midnight, January 1, 1904 (UTC)
|
SI64
ModificationTime if Version == 0
SI32
if Version == 1
SI64
The last modification time of the F4V file, expressed as seconds elapsed since midnight, January1, 1904 (UTC)
|
TimeScale
|
SI32
|
Specifies the time coordinate system
|
|
|
for the entire F4V file; for example,
| |
|
100 indicates the time units are 1/100
| ||
|
second each
| ||
|
mvhd box
Field
|
Type
|
Comment
|
|
Duration
|
if Version == 0
SI32
if Version == 1
SI64
|
The total length of the F4V file presentation with respect to the TimeScale; this value is also the duration of the longest track in the file
|
|
Rate
|
SI32
|
The preferred rate of playback, expressed as a fixed point 16.16 number (commonly 0x00010000 =
1.0, or normal playback rate)
|
|
Volume
|
SI16
|
The master volume of the file, expressed as a fixed point 8.8 number (commonly 0x0100 = 1.0, or full volume)
|
|
Reserved
|
UI16
|
Reserved, set to 0
|
|
Reserved
|
UI32[2]
|
Reserved, set to 0
|
|
Matrix
|
UI32[9]
|
Transformation matrix for the F4V file; F4V restricts these values to
{0x00010000, 0, 0, 0,
0x00010000, 0, 0, 0,
0x40000000}
|
|
Reserved
|
UI32[6]
|
Reserved, set to 0
|
|
NextTrackID
|
UI32
|
The ID of the next track to be added to the presentation; this value may not
be 0 but might be all 1’s to indicate an undefined state
|
For more information, see section 8.3 of ISO/IEC 14496–12.
trakbox
An F4V file must containone or more trak boxes. Each trak box is contained within a moov box. Eachtrak box corresponds toan individual media track within the F4V file and contains other boxes which further define theproperties ofthe media track.
|
trak box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘trak’ (0x7472616B)
|
|
Boxes
|
BOX[]
|
Arbitrary number of boxes that define the media track
|
For more information, see section8.4 of ISO/IEC 14496–12.
udta box
The optional udta boxdefines free-form user data. Flash Player does not care what is contained inthisbox. An F4V file cancontain at most one udta box.
|
udta box
Field
|
Type
|
Comment
|
|
Header
UserData
|
BOXHEADER
UI8[]
|
BoxType = ‘udta’ (0x75647461)
Free–form user data
|
For more information, seesection 8.27 of ISO/IEC 14496-12.
meta box
The optional meta box can contain a variety ofother boxes that carry metadata. An F4V filecancontain at most one meta box.
|
meta box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘meta’ (0x6D657461)
|
|
Boxes
|
BOX[]
|
Arbitrary number of boxes that define the file’s metadata
|
For more information, see section 8.44.1 of ISO/IEC 14496-12.
mdia box
Each trak box must containone and only one mdia box. The mdia box contains boxes that define media track properties.
|
mdia box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘mdia’ (0x6D646961)
|
|
Boxes
|
BOX[]
|
Arbitrary number of boxes that define media track properties
|
For more information, see section 8.7 of ISO/IEC 14496–12.
minf box
Each mdia box must contain one and only one minf box. The minf box contains boxes thatdefinethe track’s media information.
|
minf box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘minf‘ (0x6D696E66)
|
|
Boxes
|
BOX[]
|
Arbitrary number of boxes that define the track’s media information
|
For more information, see section8.10 of ISO/IEC 14496-12.
stbl box
Each minf box must contain one and only one stbl box. Thestbl box contains boxes that define properties about the samples that make up a track.
|
stbl box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘stbl’ (0x7374626C)
|
|
Boxes
|
BOX[]
|
Arbitrary number of boxes that define properties about the track’s constituent samples
|
For more information, see section8.14 of ISO/IEC 14496-12.
tkhd box
Each trak box must containone and only one tkhd box. The tkhd box describes the main properties ofa track.
|
tkhd box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘tkhd’ (0x746B6864)
|
|
Version
|
UI8
|
Versions 0 and 1 are defined
|
|
Flags
|
UI24
|
Bit 0: this bit is set if the track is enabled
Bit 1 = this bit is set if the track is part of the presentation
Bit 2 = this bit is set if the track should be considered when previewing the F4V file
|
|
CreationTime
|
if version == 0
UI32
if version == 1
|
The creation time of the track, expressed as seconds elapsed since midnight, January 1, 1904 (UTC)
|
UI64
ModificationTime if version == 0
UI32
if version == 1
UI64
The last modification time of the track,expressed as seconds elapsed since midnight, January1, 1904 (UTC)
|
TrackID Reserved
Duration
|
UI32
UI32
if version == 0
|
The track’s unique identifier
Reserved, set to 0
The duration of the track, expressed in
|
|
|
UI32
if version == 1
UI64
|
the TimeScale defined in the mvhd box for this track
|
|
Reserved
|
UI32[2]
|
Reserved, set to 0
|
|
Layer
|
SI16
|
The position if the front to back ordering of tracks; this value is expected to be 0 for F4V files
|
|
AlternateGroup
|
SI16
|
0
|
|
tkhd box
Field
|
Type
|
Comment
|
|
Volume
|
SI16
|
If the track is audio, this value is set to
0x0100 (fixed point 8.8 number representing 1.0), otherwise, it is 0
|
|
Reserved
|
SI16
|
Reserved, set to 0
|
|
TransformMatrix
|
SI32[9]
|
A matrix of fixed point 16x16 values defining a perspective transform; this matrix is restricted to the following values: {0x00010000, 0, 0, 0,
0x00010000, 0, 0, 0,
0x40000000}
|
|
Width
|
SI32
|
Applicable to a video track
|
|
Height
|
SI32
|
Applicable to a video track
|
For more information, see section 8.5 of ISO/IEC 14496–12.
mdhd box
A mdia box must containone and only one mdhd box. The mdhd box describes properties about a media track.
|
mdhd box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘mdhd’ (0x6D646864)
|
|
Version
|
UI8
|
Version 0 and 1 are supported
|
|
Flags
|
UI24
|
Reserved, set to 0
|
|
CreationTime
|
if version == 0
UI32
if version == 1
|
The creation time of the box, expressed as seconds elapsed since midnight, January 1, 1904 (UTC)
|
UI64
ModificationTime if version == 0
UI32
if version == 1
UI64
The last modification time of the box, expressedas seconds elapsed since midnight, January1, 1904 (UTC)
TimeScale UI32 The base clock tick frequency that this track uses for timing its media
|
mdhd box
Field
|
Type
|
Comment
|
|
Duration
|
if version == 0
UI32
if version == 1
UI64
|
The total duration of this track, measured in reference to the TimeScale
|
|
Pad
|
UB[1]
|
Padding, set to 0
|
|
Language
|
UB[5][3]
|
3-character code specifying language (see ISO 639-2/T); each character is interpreted as 0x60 + (5 bit) code to yield an ASCII character
|
|
Reserved
|
SI16
|
Reserved, set to 0
|
For more information, see section 8.8 of ISO/IEC 14496–12.
stsd box
The stsd box defines the sample description for a sample table. Each stbl box must containone and only one stsd box.
An stsd box can contain multipledescriptions for a track,one for each media type containedin the track.
stsd box
Field Type Comment
Header BOXHEADER BoxType = ‘stsd’ (0x73747364)Version UI8 Expected to be 0
Flags UI24 None defined, set to 0
Count UI32 The numberof entries
Descriptions DESCRIPTIONRECORD[ Count]
An array of records whose types vary depending onwhether the trackcontains audio or video data
A SAMPLEDESCRIPTION recordhasthe following layout:
SAMPLEDESCRIPTION
Field Type Comment
DescriptionLength UI32 The length of the descriptionrecord
Type UI32 The type of the description; thisvalue isoften 4 human–readable ASCII characters that also doubleas the track’scodec identifier
Description UI8[DescriptionLength–8] Per-codec configuration data
For more information, see section8.16 of ISO/IEC 14496-12.
stsc box
The stsc box defines the sample-to-chunk mapping in the sample table of a media track. An stblbox must contain one and only one stsc box.
|
stsc box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘stsc’ (0x73747363)
|
|
Version
|
UI8
|
Expected to be 0
|
|
Flags
|
UI24
|
Reserved, set to 0
|
|
Count
|
UI32
|
The number of STSCRECORD
entries
|
|
Entries
|
STSCRECORD[Count]
|
An array of STSCRECORD structures
|
Each STSCRECORD has the following format:
|
STSCRECORD
Field
|
Type
|
Comment
|
|
FirstChunk
|
UI32
|
The first chunk that this record applies to
|
|
SamplesPerChunk
|
UI32
|
The number of consecutive samples that this record applies to
|
|
SampleDescIndex
|
UI32
|
The sample description that describes this sequence of chunks
|
For more information, see section8.18 of ISO/IEC 14496-12.
stts box
The stts box defines the time-to–sample mapping for a sample table. Each stbl box mustcontain one and only one stts box.
|
stts box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘stts’ (0x73747473)
|
|
Version
|
UI8
|
Expected to be 0
|
|
Flags
|
UI24
|
None defined, set to 0
|
|
Count
|
UI32
|
The number of STTSRECORD entries
|
|
Entries
|
STTSRECORD[Count]
|
An array of STTSRECORD structures
|
|
Each STTSRECORD has the following format:
| ||
|
STTSRECORD
|
|
|
|
Field
|
Type
|
Comment
|
|
SampleCount
|
UI32
|
The number of consecutive samples that this STTSRECORD applies to
|
|
SampleDelta
|
UI32
|
Sample duration
|
For more information, see section8.15.2 of ISO/IEC 14496-12.
ctts box
The optional ctts box defines the composition time to sample mapping for a sample table. An stbl box can contain at most one ctts box.
|
ctts box
Field
|
Type
|
Comment
|
|
Header
Count
Entries
|
BOXHEADER UI32
CTTSRECORD[Count]
|
BoxType = ‘ctts‘ (0x63747473)
The number of CTTSRECORD entries
An array of CTTSRECORD structures
|
Each CTTSRECORD has the following structure:
CTTSRECORD
Field Type Comment
SampleCount UI32 The number of consecutive samples that this CTTSRECORD applies to
SampleOffset UI32 For each sample specifiedby the SampleCountfield, this field containsa positive integer that specifies the composition offset from the decoding
time
Samples are not always composed (presented to the user) at the time of decoding.The ctts boxcontains offsets from the decoding time when samples are meant to be presented to the user.
For more information, see section8.15.3 of ISO/IEC 14496-12.
stco and co64 boxes
The stco and co64 boxes define chunk offsets for each chunk in a sample table. Each sampletable must contain one and only one box of eitherthe stco or co64 type.
stco and co64 boxes
Field Type Comment
Header BOXHEADER BoxType = ‘stco’ (0x7374636F)or
‘co64‘ (0x636F3634) Version UI8 Expected to be 0
Flags UI24 No flagsdefined,set to 0
stco and co64 boxes
Field Type Comment
OffsetCount UI32 The numberof offsets in the Offsetstable
Offsets if BoxType == ‘stco’UI32[OffsetCount]
else if BoxType == ‘co64’
UI64[OffsetCount]
A table of absolute chunk offsets within the file
For more information, see section8.19 of ISO/IEC 14496-12.
stss box
The optional stss box specifies whichsamples within a sample table are sync samples. Sync samples are defined as samplesthat are safe to seek to. If the track is a video track, syncsamples are the keyframes/intraframes that do not rely onany data from any other frames.
An stbl box can containat most one stss box. If the stbl box doesn’t contain an stss box, allsamples in the track are treated as sync samples.
|
stss box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘stss’ (0x73747373)
|
|
Version
|
UI8
|
Expected to be 0
|
|
Flags
|
UI24
|
No flags defined, set to 0
|
|
SyncCount
|
UI32
|
The number of entries in SyncTable
|
|
SyncTable
|
UI32[SyncCount]
|
A table of sample numbers that are also sync samples; the table is sorted in ascending order of sample numbers
|
For more information, see section8.20 of ISO/IEC 14496-12.
stsz box
The stsz box specifies the size ofeach sample in a sample table. An stszatom must containone and only one stsz box.
|
stsz box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘stsz’ (0x7374737A)
|
|
Version
|
UI8
|
Expected to be 0
|
|
Flags
|
UI24
|
No flags defined, set to 0
|
|
ConstantSize
|
UI32
|
If all samples have the same size, this field is set with that constant size; otherwise it is 0
|
|
SizeCount
|
UI32
|
The number of entries in SizeTable
|
|
SizeTable
|
if ConstantSize == 0
UI32[SizeCount]
|
A table of sample sizes; if
ConstantSize is 0, this table is empty
|
For more information, see section8.17.2 of ISO/IEC 14496-12.
chpl box
The optional chpl box allows an F4V file tospecify individualchapters along themain timeline of an F4V file. The information in this box is provided toActionScript. The chpl box occurs within a moov box.
|
chpl box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = ‘chpl’ (0x6368706C)
|
|
Version
|
UI8
|
Expected to be 0
|
|
Flags
|
UI24
|
Reserved, set to 0
|
|
Count
|
UI8
|
The number of entries in the Chapters array
|
|
Chapters
|
CHAPTERRECORD[Count]
|
An array of timestamps along the timeline; each indicates the beginning of a new chapter
|
Each CHAPTERRECORD has the following layout:
|
CHAPTERRECORD
Field
|
Type
|
Comment
|
|
Timestamp
|
UI64
|
The absolute timestamp of the chapter, in reference to the master timescale and timeline of the F4V file
|
|
TitleSize
|
UI8
|
The length of the Title string
|
|
Title
|
UI8[TitleSize]
|
The chapter title
|
pdin box
The optional pdin box defines information about progressive download. A file can contain one pdin box at the top level of the box hierarchy. The information in this box is provided to ActionScript.
The payload of a pdin box provides hints to software about how much data to downloadbefore the software can safely begin playback.
|
pdin box
Field
|
Type
|
Comment
| |
|
Header
|
BOXHEADER
|
BoxType = ‘pdin’ (0x7064696E)
| |
|
Version
|
UI8
|
Expected to be 0
| |
|
Flags
|
UI24
|
Reserved, set to 0
| |
|
RateDelay
|
RATEDELAYRECORD[]
|
Populated until the end of the box
| |
|
Each RATEDELAYRECORD has the following layout:
| |||
|
RATEDELAYRECORD
|
|
| |
|
Field
|
Type
|
Comment
| |
|
BitRate
|
UI32
|
The bit rate (in bytes/second) to be considered for this record
| |
|
InitialDelay
|
UI32
|
The number of milliseconds to delay before beginning playback at this bit rate
| |
For more information, see section8.43 of ISO/IEC 14496-12.
mdat box
An mdat box contains the media datapayload for the F4V file. An F4V file must contain one and only one mdat box. The mdat box occurs at the top level ofan F4V file, along with the moov box.
The mdat box cannot be understood on its own, which is why amoov box must be present inthe file as well.
|
mdat box
|
| |
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘mdat’ (0x6D646174)
|
|
Payload
|
UI8[n]
|
n bytes of media data, the structure of which is defined in the file’s moov box
|
For more information, see section 8.2 of ISO/IEC 14496–12
Required structure
Flash Player expects a valid F4V file to begin with the one of the following top-level boxes:
■ ftyp (see “ftyp box” on page 18)
■ moov (see “moov box” on page 19)
■ mdat (see “mdat box” on page 32)
Many tools that create these files place anmdat box at the front of the file. Before Flash Player canusethe file, it is necessary tochangethe order of boxes in the file. Some tools store anftyp box followed immediately by an mdat box. Inthese situations, itis still recommended to use a post-processing step to move themoov box to the frontof the file (just after the ftyp box).
Supported media types
The following table describes themedia types that Flash Player plays back when the media is encapsulated inside anF4V file.
Media type Comments
GIF A media type of gif (0x67696620) denotes a still frame of video data compressedusing the CompuServeGIF format. The space character, hex 0x20, is includedto make a completefour-character code.
PNG A media type of png (0x706E6720) denotes a still frame of video data compressedusing the standardPNG format. The spacecharacter,
hex 0x20, isincluded to make a completefour-character code.
JPEG A media type of jpeg (0x6A706567) denotes a still frame of video datacompressed using the standard JPEG format.
Text A media type of either text (0x74657874) or tx3g (0x74783367) indicates that thetrack contains textual data that is made available via ActionScript.
AMF0 A media type of amf0 (0x616D6630)indicatesthat the track contains data corresponding to the original version of the ActionScript MessageFormat (AMF).
AMF3 A media type of amf3 (0x616D6633) indicates that the track contains data corresponding to the ActionScript MessageFormat (AMF) version 3.
H.264 A media type of H264 (0x48323634), h264 (0x68323634), oravc1 (0x61766331) indicates that the track is encoded with H.264 video.FlashPlayer supports the following H.264 video profiles:
• 0: supported for older media that neglects toset profile
• 66: baseline
• 77: extended
• 88: main
• 100: YUV 4:2:0, 8 bits/sample; a.k.a.“High”
• 110: YUV 4:2:0, 10 bits/sample;a.k.a. “High 10”
• 122: YUV 4:2:2, 10 bits/sample; a.k.a. “High 4:2:2”
• 144: YUV 4:4:4, 12 bits/sample; a.k.a. “High 4:4:4”
Media type Comments
MP3 A media type of .mp3 (0x2E6D7033) indicates that the trackcontains MP3 audio data. The dot character, hex 0x2E, is includedto make a complete four-charactercode.
AAC
(Flash Player
9,0,115,0 and higher)
A media type of mp4a (0x6D703461) indicates that the track isencoded with AAC audio. Flash Playersupports the following AAC profiles, denoted bytheirobject types:
• 1: main profile
• 2: low complexity,a.k.a. LC
• 5: high efficiency/scale band replication, a.k.a.HE/SBR
An avcC box occurs inside the stsd box of a sample table when the video codec is H.264, and contains initialization data that an H.264 decoder requires todecodethe stream. Bytes 1
and 3 after the BOXHEADER contain the profile and level, respectively, for the AVC data. For more information aboutthe remainder ofthe avcC box, see section5.3.4.1 of ISO/IEC
14496–15.
An esds box occurs inside the stsd box of a sample table when the actioncodecis AAC, and contains initialization data that an AAC decoder requires to decode the stream. See ISO/IEC
14496–3 for more informationabout the structure of this box.
Unsupported boxes
Many box types are described in the formal ISO specification, as well as in the original AppleQuickTime specification, that Flash Player does notacknowledge. Flash Player might still play files with these box types, but gracefully disregards these boxes andtheir contents.
CHAPTER 3
|
F4V Metadata
When Flash Player loads an F4V file, various stream properties are made availableto a running ActionScript program via the NetStream.onMetaData property. The availableproperties differ depending on the software used. These properties are:
■ duration: a DOUBLE indicating the totallength of the movie inseconds
■ moovposition: a DOUBLE indicating theabsolute offsetof the moov box within the
F4V file; this property is useful for determining ifthe file will load progressively
■ videocodecid: a STRING with four characters that define the video codec used, if video ispresent and is encoded with a codec that Flash Player can decode
■ width: a DOUBLE indicating the width of the video, if video ispresent and is encodedwith a codec that Flash Player can decode
■ height: a DOUBLEindicating theheight of the video, if video is present and is encoded with a codec that Flash Player can decode
■ avcprofile: a DOUBLE indicating the AVC profile that the video conforms to, if video is present and is encoded with AVC/H.264
■ avclevel: a DOUBLE indicating the AVC level that the video conforms to, if video is present and is encoded with AVC/H.264
■ videoframerate: a DOUBLEindicating theaverage video frame rate of the video, ifvideo is present and is encoded with a codec that Flash Player candecode
■ audiocodecid: a STRING with four characters that define the audio codec used, if audio is present and is encoded with a codec that Flash Player can decode
Tag box
The F4V file format supports an assortment ofoptional tag boxes that can occur within a moov box. AnFLV file cancontain up to 256 tags (includingthe tags in these boxesand the tags defined inan ilst box).
.
Tag box
|
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxType = one of several
|
|
Version
|
UI8
|
Must be 0
|
|
Flags
|
UI24
|
Reserved, set to 0
|
|
LanguageCode
|
UI16
|
ISO-639-2/T two-letter codes
|
|
TagString
|
UI8[n]
|
n = remaining size of the box when the tag is reached; the maximum size that the Player honors for a TagString is
65535 bytes
|
These tags can occur one level beneath a moov box. Recognized tag types include ‘auth’ (0x61757468), ‘titl’ (0x7469746C), ‘dscp’ (0x64736370), and ‘cprt’ (0x63707274).
ilst box
An ilst box occurs inside a meta box and contains anarbitrary number of metadata tags thatare availableto ActionScript. AnFLV file can contain up to 256 tags (including the tags in this box and in the auth,dscp, andcprt tag box types).
.
|
ilst box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘ilst‘ (0x696C7374)
|
|
TagCount
|
UI32
|
The number of tags enumerated in the ilst box
|
|
Tags
|
TAGRECORD[TagCount]
|
A number of TAGRECORD entries
|
Each TAGRECORD has the following layout:
|
TAGRECORD
Field
|
Type
|
Comment
|
|
TagLength
|
UI32
|
The total length of the TAGRECORD, including this length field
|
|
TagName
|
UI8[4]
|
4 bytes indicating the name of the tag; these bytes usually come from the human-readable ASCII set, but not always
|
|
DataLength
|
UI32
|
The total length of the data portion of the TAGRECORD
|
|
DataTag
|
UI8[4]
|
The 4 bytes ‘d’, ‘a’, ‘t’, and ‘a’ to indicate the data portion of the TAGRECORD
|
|
DataType
|
UI32
|
Specifies the type of data in the data payload of the TAGRECORD
|
|
Reserved
|
UI32
|
Reserved, set to 0
|
|
Payload
|
UI8[]
|
An arbitrary number of bytes occupying the remainder of the TAGRECORD; the precise payload format is dependent on the DataType
|
The supported values for the DataType are:
■ 0: custom data; in the case of‘trkn’ and ‘disk’ tag types, the data payload is interpreted as a single UI32
■ 1: text data
■ 13, 14: binary data
■ 21: generic data
Image metadata
If an F4V sample is an image type (GIF, PNG, or JPEG), the data is made available to a running ActionScriptprogram throughthe onImageData property. The following properties are present:
■ trackid: a DOUBLE indicating the track that this sample belongs to
■ data: a BYTEARRAY containing the compressed image data (that is, the original JPEG, PNG or GIFfile data)
Text metadata
Text samples (‘text’ or ‘tx3g’) can contain a wide range ofmetadata boxes whosecontents are exposed toa running ActionScript program through the onTextData property.
styl box
A styl box carries text style specifications. This information is exposed toActionScript via the
style property.
|
styl box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘styl’ (0x7374796C)
|
|
Count
|
UI16
|
The number of entries in the Styles array
|
|
Styles
|
STYLERECORD[Count]
|
An array of STYLERECORD structures; each is exposed as an ActionScript object
|
|
An individual STYLERECORD has the following layout:
| ||
|
STYLERECORD
|
|
|
|
Field
|
Type
|
Comment
|
|
StartChar
|
UI16
|
The first character to which this STYLERECORD applies; exposed to ActionScript via a DOUBLE property named startchar
|
|
EndChar
|
UI16
|
The last character to which this STYLERECORD applies; exposed to ActionScript via a DOUBLE property named endchar
|
|
FontID
|
UI16
|
The font ID to use for this style; exposed to ActionScript via a DOUBLE property named fontid
|
|
FaceStyleFlags
|
UI8
|
Exposed to ActionScript via a
DOUBLE property named
|
|
|
|
facestyleflags
|
|
STYLERECORD
Field
|
Type
|
Comment
|
|
FontSize
|
UI8
|
The size to use for the font; exposed to
ActionScript via the property
|
|
|
|
fontsize
|
|
TextColor
|
UI32
|
The RGBA color for the text; exposed to ActionScript via the property
|
|
|
|
textcolor
|
hlit box
An hlit box specifies a range oftext to be highlighting. This information is exposedto
ActionScript via the highlight property.
|
hlit box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘hlit’ (0x686C6974)
|
|
StartChar
|
UI16
|
The first character to highlight; exposed to ActionScript via a DOUBLE property named startchar
|
|
EndChar
|
UI16
|
The final character to highlight; exposed to ActionScript via a DOUBLE property named endchar
|
hclr box
An hclr box specifies the highlight color for text. This information is exposed to ActionScript via the highlightcolor property.
|
hclr box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘hclr’ (0x68636C72)
|
|
HighlightColor
|
UI16[3]
|
A three-element array that holds values for red, green, and blue components in that order; exposed to ActionScript via a DOUBLE property named highlightcolor
|
krok box
A krok box specifies karaoke metadata. This information isexposed to ActionScript via the
karaoke property. Times are expressed intimescale units in relation tothe track.
|
krok box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘krok’ (0x6B726F6B)
|
|
StartTime
|
UI32
|
Exposed to ActionScript via a
DOUBLE property named starttime
|
|
Count
|
UI16
|
The number of entries in the
KaraokeRecords array
|
|
KaraokeRecords
|
KARAOKEREC[Count]
|
An array of KARAOKEREC structures; each is exposed to ActionScript as an object
|
|
An individual KARAOKEREC has the following structure:
| ||
|
KARAOKEREC
|
|
|
|
Field
|
Type
|
Comment
|
|
EndTime
|
UI32
|
Exposed to ActionScript via a
DOUBLE property named endtime
|
|
StartChar
|
UI16
|
Exposed to ActionScript via a
DOUBLE property named startchar
|
|
EndChar
|
UI16
|
Exposed to ActionScript via a
DOUBLE property named endchar
|
dlay box
A dlay box specifies ascroll delay. This information is exposed to ActionScript via the
scrolldelay property, expressedin timescale units in relation to the track.
|
dlay box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘dlay’ (0x646C6179)
|
|
ScrollDelay
|
UI32
|
Exposed to ActionScript via a
DOUBLE property named
|
|
|
|
scrolldelay
|
drpo box
A drpo box specifies drop shadow offset coordinatesfor text.
|
drpo box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘drpo’ (0x6472706F)
|
|
DropShadowOffsetX
|
UI16
|
Exposed to ActionScript via a
DOUBLE property named
|
|
|
|
dropshadowoffsetx
|
|
DropShadowOffsetY
|
UI16
|
Exposed to ActionScript via a
DOUBLE property named
|
|
|
|
dropshadowoffsety
|
drpt box
A drpt box specifies drop shadow alpha value.
|
drpt box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘drpt‘ (0x64727074)
|
|
DropShadowAlpha
|
UI16
|
A 16-bit alpha value; exposed to ActionScript via a DOUBLE property named dropshadowalpha
|
href box
An href box specifies ahypertext link with ALT text over a text range. This information is exposed to ActionScript via the hypertext property.
|
href box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘href’ (0x68726566)
|
|
StartChar
|
UI16
|
The beginning character of the text range; exposed to ActionScript via a DOUBLE property named startchar
|
|
EndChar
|
UI16
|
The last character of the text range; exposed to ActionScript via a DOUBLE property named endchar
|
|
href box
Field
|
Type
|
Comment
|
|
URLSize
|
UI8
|
The length of the URL string
|
|
URL
|
UI8[URLSize]
|
The URL string; exposed to ActionScript via a STRING property named url
|
|
ALTSize
|
UI8
|
The length of the ALT string
|
|
ALT
|
UI8[ALTSize]
|
The ALT string which is displayed when the user’s mouse hovers over the link; exposed to ActionScript via a STRING property named alt
|
tbox box
A tbox box defines the coordinates fora text box. This information is exposedto ActionScript via the textbox property.
|
tbox box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘tbox’ (0x74626F78)
|
|
Top
|
UI16
|
The top pixel coordinate; exposed to ActionScript via a DOUBLE property named top
|
|
Left
|
UI16
|
The left pixel coordinate; exposed to ActionScript via a DOUBLE property named left
|
|
Bottom
|
UI16
|
The bottom pixel coordinate; exposed to ActionScript via a DOUBLE property named bottom
|
|
Right
|
UI16
|
The right pixel coordinate; exposed to ActionScript via a DOUBLE property named right
|
blnk box
A blnk box specifies arangeof text to set blinking. This information is exposed to
ActionScript via the blink property.
|
blnk box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘blnk’ (0x626C6E6B)
|
|
StartChar
|
UI16
|
The first character in the blinking range; exposed to ActionScript via a DOUBLE property named startchar
|
|
EndChar
|
UI16
|
The ending character in the blinking range; exposed to ActionScript via a DOUBLE property named endchar
|
twrp box
A twrp box sets thewrap flag for text.
|
twrp box
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘twrp’ (0x74777270)
|
|
WrapFlag
|
UI8
|
A boolean that is nonzero if the text should wrap; exposed to ActionScript via a DOUBLE property named
|
|
|
|
wrapflag
|
XMP Metadata
Beginning in version 10, Flash Player can load XMP data embedded in an F4V file. XMP is
Adobe’s Extensible Metadata Platform. For more information, see www.adobe.com/go/xmp.
uuid box
A uuid box exists at the top level ofan F4V file and is the methodby which the file can communicate XMP metadata to a SWF movie via ActionScript.
|
uuid
Field
|
Type
|
Comment
|
|
Header
|
BOXHEADER
|
BoxHeader = ‘uuid’ (0x75756964)
|
|
UUID
|
UI8[16]
|
A 16–byte (128-bit) universally unique identifier (UUID). The UUID that must appear here consists of these hexadecimal bytes: BE 7A CF CB 97
A9 42 A8 9C 71 99 94 91 E3 AF AC.
|
|
XMPMetadata
|
UI8[]
|
XMP metadata, formatted according to the XMP metadata standard; exposed to ActionScript via a STRING property named data
|
Note that the maximum allowed size ofan XMP metadata boxis 64 megabytes.
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