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693 lines
41 KiB
693 lines
41 KiB
4 months ago
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<link rel="stylesheet" type="text/css" href="opus_in_isobmff.css"/>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Encapsulation of Opus in ISO Base Media File Format</title>
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</head>
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<body bgcolor="0x333333" text="#60B0C0">
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<b><u>Encapsulation of Opus in ISO Base Media File Format</u></b><br>
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<font size="2">last updated: August 28, 2018</font><br>
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<br>
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<div class="normal_link pre frame_box">
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Encapsulation of Opus in ISO Base Media File Format
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Version 0.8.1 (incomplete)
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Table of Contents
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<a href="#1">1</a> Scope
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<a href="#2">2</a> Normative References
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<a href="#3">3</a> Terms and Definitions
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<a href="#4">4</a> Design Rules of Encapsulation
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<a href="#4.1">4.1</a> File Type Identification
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<a href="#4.2">4.2</a> Overview of Track Structure
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<a href="#4.3">4.3</a> Definitions of Opus sample
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<a href="#4.3.1">4.3.1</a> Sample entry format
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<a href="#4.3.2">4.3.2</a> Opus Specific Box
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<a href="#4.3.3">4.3.3</a> Sample format
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<a href="#4.3.4">4.3.4</a> Duration of Opus sample
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<a href="#4.3.5">4.3.5</a> Sub-sample
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<a href="#4.3.6">4.3.6</a> Random Access
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<a href="#4.3.6.1">4.3.6.1</a> Random Access Point
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<a href="#4.3.6.2">4.3.6.2</a> Pre-roll
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<a href="#4.4">4.4</a> Trimming of Actual Duration
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<a href="#4.5">4.5</a> Channel Mapping
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<a href="#4.5.1">4.5.1</a> ISO Base Media native Channel Mapping
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<a href="#4.5.2">4.5.2</a> Composition on all active tracks (informative)
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<a href="#4.6">4.6</a> Basic Structure (informative)
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<a href="#4.6.1">4.6.2</a> Initial Movie
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<a href="#4.6.2">4.6.3</a> Movie Fragments
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<a href="#4.7">4.7</a> Example of Encapsulation (informative)
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<a href="#5">5</a> Author's Address
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<a name="1"></a>
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1 Scope
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This specification specifies the fundamental way of the encapsulation of Opus coded bitstreams in ISO Base Media
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file format and its derivatives. The encapsulation of Opus coded bitstreams in QuickTime file format is outside
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the scope of this specification.
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<a name="2"></a>
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2 Normative References
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[1] ISO/IEC 14496-12:2015 Corrected version
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Information technology — Coding of audio-visual objects — Part 12: ISO base media file format
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[2] RFC 6716
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Definition of the Opus Audio Codec
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[3] RFC 7845
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Ogg Encapsulation for the Opus Audio Codec
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<a name="3"></a>
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3 Terms and Definitions
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3.1 active track
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enabled track from the non-alternate group or selected track from alternate group
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3.2 actual duration
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duration constructed from valid samples
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3.3 edit
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entry in the Edit List Box
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3.4 padded samples
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PCM samples after decoding Opus sample(s) which are not valid samples
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An Opus bitstream always contains them partially at the beginning and may contain them in part at the end, as
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long as not physically removed yet at the beginning and/or the end.
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3.5 priming samples
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padded samples at the beginning of the Opus bitstream
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3.6 sample-accurate
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for any PCM sample, a timestamp exactly matching its sampling timestamp is present in the media timeline.
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3.7 valid samples
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PCM samples after decoding Opus sample(s) corresponding to input PCM samples
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<a name="4"></a>
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4 Design Rules of Encapsulation
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4.1 File Type Identification<a name="4.1"></a>
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This specification defines the brand 'Opus' to declare files are conformant to this specification. Additionally,
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files conformant to this specification shall contain at least one brand, which supports the requirements and the
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requirements described in this clause without contradiction, in the compatible brands list of the File Type Box.
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As an example, the minimal support of the encapsulation of Opus bitstreams in ISO Base Media file format requires
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the 'iso2' brand in the compatible brands list since support of roll groups is required.
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<a name="4.2"></a>
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4.2 Overview of Track Structure
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This clause summarizes requirements of the encapsulation of Opus coded bitstream as media data in audio tracks
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in file formats compliant with the ISO Base Media File Format. The details are described in clauses after this
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clause.
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+ The handler_type field in the Handler Reference Box shall be set to 'soun'.
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+ The Media Information Box shall contain the Sound Media Header Box.
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+ The codingname of the sample entry is 'Opus'.
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This specification does not define any encapsulation using MP4AudioSampleEntry with objectTypeIndication
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specified by the MPEG-4 Registration Authority (http://www.mp4ra.org/).
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See 4.3.1 Sample entry format to get the details about the sample entry.
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+ The 'dOps' box is added to the sample entry to convey initializing information for the decoder.
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See 4.3.2 Opus Specific Box to get the details.
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+ An Opus sample is exactly one Opus packet for each of different Opus bitstreams.
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See 4.3.3 Sample format to get the details.
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+ Every Opus sample is a sync sample but requires pre-roll for every random access to get correct output.
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See 4.3.6 Random Access to get the details.
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<a name="4.3"></a>
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4.3 Definitions of Opus sample
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4.3.1 Sample entry format<a name="4.3.1"></a>
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For any track containing Opus bitstreams, at least one sample entry describing corresponding Opus bitstream
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shall be present inside the Sample Table Box. This version of the specification defines only one sample
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entry format named OpusSampleEntry whose codingname is 'Opus'. This sample entry includes exactly one Opus
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Specific Box defined in 4.3.2 as a mandatory box and indicates that Opus samples described by this sample
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entry are stored by the sample format described in 4.3.3.
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The syntax and semantics of the OpusSampleEntry is shown as follows.
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class OpusSampleEntry() extends AudioSampleEntry ('Opus') {
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OpusSpecificBox();
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}
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+ channelcount:
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The channelcount field indicates the number of output channels and shall be set to the same value of
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the OutputChannelCount in the OpusDecoderConfigurationRecord. The value of this field may be used in
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the ChannelLayout if any as described in 4.5.1.
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+ samplesize:
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The samplesize field shall be set to 16.
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+ samplerate:
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The samplerate field shall be set to 48000<<16.
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+ OpusSpecificBox
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This box contains initializing information for the decoder as defined in 4.3.2.
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4.3.2 Opus Specific Box<a name="4.3.2"></a>
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Exactly one Opus Specific Box shall be present in each OpusSampleEntry.
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The Opus Specific Box contains an OpusDecoderConfigurationRecord which contains the Version field and
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this specification defines version 0 of this record. If incompatible changes occured in the fields after
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the Version field within the OpusDecoderConfigurationRecord in the future versions of this specification,
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another version will be defined.
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This box refers to Ogg Opus [3] at many parts but all the data are stored as big-endian format.
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The syntax and semantics of the Opus Specific Box is shown as follows.
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class ChannelMappingTable (unsigned int(8) OutputChannelCount) {
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unsigned int(8) StreamCount;
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unsigned int(8) CoupledCount;
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unsigned int(8 * OutputChannelCount) ChannelMapping;
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}
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aligned(8) class OpusDecoderConfigurationRecord {
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unsigned int(8) Version;
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unsigned int(8) OutputChannelCount;
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unsigned int(16) PreSkip;
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unsigned int(32) InputSampleRate;
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signed int(16) OutputGain;
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unsigned int(8) ChannelMappingFamily;
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if (ChannelMappingFamily != 0) {
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ChannelMappingTable(OutputChannelCount);
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}
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}
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class OpusSpecificBox extends Box('dOps') {
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OpusDecoderConfigurationRecord() OpusConfig;
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}
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+ Version:
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The Version field shall be set to 0.
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In the future versions of this specification, this field may be set to other values. And without support
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of those values, the reader shall not read the fields after this within the OpusSpecificBox.
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+ OutputChannelCount:
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The OutputChannelCount field shall be set to the same value as the *Output Channel Count* field in the
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identification header defined in Ogg Opus [3].
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+ PreSkip:
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The PreSkip field indicates the number of the priming samples, that is, the number of samples at 48000 Hz
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to discard from the decoder output when starting playback. The value of the PreSkip field shall be at least
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80 milliseconds' worth of PCM samples even when removing any number of Opus samples which may or may not
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contain the priming samples. The PreSkip field is not used for discarding the priming samples at the whole
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playback at all since it is informative only, and that task falls on the Edit List Box.
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+ InputSampleRate:
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The InputSampleRate field shall be set to the same value as the *Input Sample Rate* field in the
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identification header defined in Ogg Opus [3].
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+ OutputGain:
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The OutputGain field shall be set to the same value as the *Output Gain* field in the identification
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header define in Ogg Opus [3]. Note that the value is stored as 8.8 fixed-point.
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+ ChannelMappingFamily:
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The ChannelMappingFamily field shall be set to the same value as the *Channel Mapping Family* field in
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the identification header defined in Ogg Opus [3]. Note that the value 255 may be used for an alternative
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to map channels by ISO Base Media native mapping. The details are described in 4.5.1.
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+ StreamCount:
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The StreamCount field shall be set to the same value as the *Stream Count* field in the identification
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header defined in Ogg Opus [3].
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+ CoupledCount:
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The CoupledCount field shall be set to the same value as the *Coupled Count* field in the identification
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header defined in Ogg Opus [3].
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+ ChannelMapping:
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The ChannelMapping field shall be set to the same octet string as *Channel Mapping* field in the identi-
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fication header defined in Ogg Opus [3].
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4.3.3 Sample format<a name="4.3.3"></a>
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An Opus sample is exactly one Opus packet for each of different Opus bitstreams. Due to support more than
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two channels, an Opus sample can contain frames from multiple Opus bitstreams but all Opus packets shall
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share with the total of frame sizes in a single Opus sample. The way of how to pack an Opus packet from
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each of Opus bitstreams into a single Opus sample follows Appendix B. in RFC 6716 [2].
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The endianness has nothing to do with any Opus sample since every Opus packet is processed byte-by-byte.
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In this specification, 'sample' means 'Opus sample' except for 'padded samples', 'priming samples', 'valid
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sample' and 'sample-accurate', i.e. 'sample' is 'sample' in the term defined in ISO/IEC 14496-12 [1].
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+-----------------------------------------+-------------------------------------+
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| Opus packet 0 (self-delimiting framing) | Opus packet 1 (undelimited framing) |
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+-----------------------------------------+-------------------------------------+
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|<---------------------------- the size of Opus sample ------------------------>|
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Figure 1 - Example structure of an Opus sample containing two Opus bitstreams
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4.3.4 Duration of Opus sample<a name="4.3.4"></a>
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The duration of Opus sample is given by multiplying the total of frame sizes for a single Opus bitstream
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expressed in seconds by the value of the timescale field in the Media Header Box.
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Let's say an Opus sample consists of two Opus bitstreams, where the frame size of one bitstream is 40 milli-
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seconds and the frame size of another is 60 milliseconds, and the timescale field in the Media Header Box
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is set to 48000, then the duration of that Opus sample shall be 120 milliseconds since three 40 millisecond
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frame and two 60 millisecond frames shall be contained because of the maximum duration of Opus packet, 120
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milliseconds, and 5760 in the timescale indicated in the Media Header Box.
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To indicate the valid samples excluding the padded samples at the end of Opus bitstream, the duration of
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the last Opus sample of an Opus bitstream is given by multiplying the number of the valid samples by the
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value produced by dividing the value of the timescale field in the Media Header Box by 48000.
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4.3.5 Sub-sample<a name="4.3.5"></a>
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The structure of the last Opus packet in an Opus sample is different from the others in the same Opus sample,
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and the others are invalid Opus packets as an Opus sample because of self-delimiting framing. To avoid
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complexities, sub-sample is not defined for Opus sample in this specification.
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4.3.6 Random Access<a name="4.3.6"></a>
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This subclause describes the nature of the random access of Opus sample.
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4.3.6.1 Random Access Point<a name="4.3.6.1"></a>
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All Opus samples can be independently decoded i.e. every Opus sample is a sync sample. Therefore, the
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Sync Sample Box shall not be present as long as there are no samples other than Opus samples in the same
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track. And the sample_is_non_sync_sample field for Opus samples shall be set to 0.
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4.3.6.2 Pre-roll<a name="4.3.6.2"></a>
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Opus bitstream requires at least 80 millisecond pre-roll after each random access to get correct output.
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Pre-roll is indicated by the roll_distance field in AudioRollRecoveryEntry. AudioPreRollEntry shall not
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be used since every Opus sample is a sync sample in Opus bitstream. Note that roll_distance is expressed
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in sample units in a term of ISO Base Media File Format, and always takes negative values.
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For any track containing Opus bitstreams, at least one Sample Group Description Box and at least one
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Sample to Group Box within the Sample Table Box shall be present and these have the grouping_type field
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set to 'roll'. If any Opus sample is contained in a track fragment, the Sample to Group Box with the
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grouping_type field set to 'roll' shall be present for that track fragment.
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For the requirement of AudioRollRecoveryEntry, the compatible_brands field in the File Type Box shall
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contain at least one brand which requires support for roll groups.
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<a name="4.4"></a>
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4.4 Trimming of Actual Duration
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Due to the priming samples (or the padding at the beginning) derived from the pre-roll for the startup and the
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padded samples at the end, we need trim from media to get the actual duration. An edit in the Edit List Box can
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achieve this demand, and the Edit Box and the Edit List Box shall be present.
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For sample-accurate trimming, proper timescale should be set to the timescale field in the Movie Header Box
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and the Media Header Box inside Track Box(es) for Opus bitstream. The timescale field in the Media Header Box is
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typically set to 48000. It is recommended that the timescale field in the Movie Header Box be set to the same
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value of the timescale field in the Media Header Box in order to avoid the rounding problem when specifying
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duration of edit if the timescales in all of the Media Header Boxes are set to the same value.
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For example, to indicate the actual duration of an Opus bitstream in a track with the timescale fields of both
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the Movie Header Box and the Media Header Box set to 48000, we would use the following edit:
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segment_duration = the number of the valid samples
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media_time = the number of the priming samples
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media_rate = 1 << 16
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The Edit List Box is applied to whole movie including all movie fragments. Therefore, it is impossible to tell
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the actual duration in the case producing movie fragments on the fly such as live-streaming. In such cases,
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the duration of the last Opus sample may be helpful by setting zero to the segment_duration field since the
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value 0 represents implicit duration equal to the sum of the duration of all samples.
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<a name="4.5"></a>
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4.5 Channel Mapping
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4.5.1 ISO Base Media native Channel Mapping<a name="4.5.1"></a>
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ISO Base Media File Format, that is ISO/IEC 14496-12 [1], defines an extension ChannelLayout to the
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AudioSampleEntry, which conveys information of mapping channels to loudspeaker positions. The ChannelLayout
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enables to specify the channel layout more flexibly than the predefined layouts of the ChannelMappingFamily.
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To utilize the ChannelLayout for OpusSampleEntry, the ChannelMappingFamily field should be set to 255.
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Even when the ChannelMappingFamily field is set to another value, the assignment of each output channel to
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loudspeaker position specified by the ChannelMappingFamily would be changed as specified by the ChannelLayout.
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The procedure of the assignment is the following.
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1. Decoded channels are mapped to output channels according to the ChannelMappingTable.
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2. Output channels are mapped to loudspeaker positions according to the ChannelLayout.
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In this way, the parameters of the Opus Specific Box are processed before the ChannelLayout, and the
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ChannelLayout shall follow the Opus Specific Box.
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4.5.2 Composition on all active tracks (informative)<a name="4.5.2"></a>
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|
|
By the application of alternate_group in the Track Header Box, whole audio channels in all active tracks from
|
||
|
|
non-alternate group and/or different alternate group from each other are composited into the presentation. If
|
||
|
|
an Opus sample consists of multiple Opus bitstreams, it can be splitted into individual Opus bitstreams and
|
||
|
|
reconstructed into new Opus samples as long as every Opus bitstream has the same total duration in each Opus
|
||
|
|
sample. This nature can be utilized to encapsulate a single Opus bitstream in each track without breaking the
|
||
|
|
original channel layout.
|
||
|
|
|
||
|
|
As an example, let's say there is a following track:
|
||
|
|
OutputChannelCount = 6;
|
||
|
|
StreamCount = 4;
|
||
|
|
CoupledCount = 2;
|
||
|
|
ChannelMapping = {0, 4, 1, 2, 3, 5}; // front left, front center, front right,
|
||
|
|
// rear left, rear right, LFE
|
||
|
|
Here, to couple front left to front right channels into the first stream, and couple rear left to rear right
|
||
|
|
channels into the second stream, reordering is needed since coupled streams must precede any non-coupled
|
||
|
|
stream. You extract the four Opus bitstreams from this track and you encapsulate two of the four into a track
|
||
|
|
and the others into another track. The former track is as follows.
|
||
|
|
OutputChannelCount = 6;
|
||
|
|
StreamCount = 2;
|
||
|
|
CoupledCount = 2;
|
||
|
|
ChannelMapping = {0, 255, 1, 2, 3, 255}; // front left, front center, front right,
|
||
|
|
// rear left, rear right, LFE
|
||
|
|
And the latter track is as follows.
|
||
|
|
OutputChannelCount = 6;
|
||
|
|
StreamCount = 2;
|
||
|
|
CoupledCount = 0;
|
||
|
|
ChannelMapping = {255, 0, 255, 255, 255, 1}; // front left, front center, front right,
|
||
|
|
// rear left, rear right, LFE
|
||
|
|
In addition, the value of the alternate_group field in the both tracks is set to 0. As the result, the player
|
||
|
|
may play as if channels with 255 are not present, and play the presentation constructed from the both tracks
|
||
|
|
in the same channel layout as the one of the original track. Keep in mind that the way of the composition, i.e.
|
||
|
|
the mixing for playback, is not defined here, and maybe different results could occur except for the channel
|
||
|
|
layout of the original, depending on an implementation or the definition of a derived file format.
|
||
|
|
|
||
|
|
Note that some derived file formats may specify the restriction to ignore alternate grouping. In the context
|
||
|
|
of such file formats, this application is not available. This unavailability does not mean incompatibilities
|
||
|
|
among file formats unless the restriction to the value of the alternate_group field is specified and brings
|
||
|
|
about any conflict among their definitions.
|
||
|
|
<a name="4.6"></a>
|
||
|
|
4.6 Basic Structure (informative)
|
||
|
|
4.6.1 Initial Movie<a name="4.6.1"></a>
|
||
|
|
This subclause shows a basic structure of the Movie Box as follows:
|
||
|
|
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
|moov| | | | | | | | Movie Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| |mvhd| | | | | | | Movie Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| |trak| | | | | | | Track Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |tkhd| | | | | | Track Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |edts| | | | | | Edit Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | |elst| | | | | Edit List Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |mdia| | | | | | Media Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | |mdhd| | | | | Media Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | |hdlr| | | | | Handler Reference Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | |minf| | | | | Media Information Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | |smhd| | | | Sound Media Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | |dinf| | | | Data Information Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |dref| | | Data Reference Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | | |url | | DataEntryUrlBox |
|
||
|
|
+----+----+----+----+----+----+ or +----+------------------------------+
|
||
|
|
| | | | | | |urn | | DataEntryUrnBox |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | |stbl| | | | Sample Table |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |stsd| | | Sample Description Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | | |Opus| | OpusSampleEntry |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | | | |dOps| Opus Specific Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |stts| | | Decoding Time to Sample Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |stsc| | | Sample To Chunk Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |stsz| | | Sample Size Box |
|
||
|
|
+----+----+----+----+----+ or +----+----+------------------------------+
|
||
|
|
| | | | | |stz2| | | Compact Sample Size Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |stco| | | Chunk Offset Box |
|
||
|
|
+----+----+----+----+----+ or +----+----+------------------------------+
|
||
|
|
| | | | | |co64| | | Chunk Large Offset Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |sgpd| | | Sample Group Description Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | | | | |sbgp| | | Sample to Group Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| |mvex|* | | | | | | Movie Extends Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |trex|* | | | | | Track Extends Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
|
||
|
|
Figure 2 - Basic structure of Movie Box
|
||
|
|
|
||
|
|
It is strongly recommended that the order of boxes should follow the above structure.
|
||
|
|
Boxes marked with an asterisk (*) may be present.
|
||
|
|
For most boxes listed above, the definition is as is defined in ISO/IEC 14496-12 [1]. The additional boxes
|
||
|
|
and the additional requirements, restrictions and recommendations to the other boxes are described in this
|
||
|
|
specification.
|
||
|
|
|
||
|
|
4.6.2 Movie Fragments<a name="4.6.2"></a>
|
||
|
|
This subclause shows a basic structure of the Movie Fragment Box as follows:
|
||
|
|
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
|moof| | | | | | | | Movie Fragment Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| |mfhd| | | | | | | Movie Fragment Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| |traf| | | | | | | Track Fragment Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |tfhd| | | | | | Track Fragment Header Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |trun| | | | | | Track Fragment Run Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |sgpd|* | | | | | Sample Group Description Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
| | |sbgp| | | | | | Sample to Group Box |
|
||
|
|
+----+----+----+----+----+----+----+----+------------------------------+
|
||
|
|
|
||
|
|
Figure 3 - Basic structure of Movie Fragment Box
|
||
|
|
|
||
|
|
It is strongly recommended that the Movie Fragment Header Box and the Track Fragment Header Box be
|
||
|
|
placed first in their container.
|
||
|
|
Boxes marked with an asterisk (*) may be present.
|
||
|
|
For the boxes listed above, the definition is as is defined in ISO/IEC 14496-12 [1].
|
||
|
|
<a name="4.7"></a>
|
||
|
|
4.7 Example of Encapsulation (informative)
|
||
|
|
[File]
|
||
|
|
size = 17757
|
||
|
|
[ftyp: File Type Box]
|
||
|
|
position = 0
|
||
|
|
size = 24
|
||
|
|
major_brand = Opus : Opus audio coding
|
||
|
|
minor_version = 0
|
||
|
|
compatible_brands
|
||
|
|
brand[0] = Opus : Opus audio coding
|
||
|
|
brand[1] = iso2 : ISO Base Media file format version 2
|
||
|
|
[moov: Movie Box]
|
||
|
|
position = 24
|
||
|
|
size = 757
|
||
|
|
[mvhd: Movie Header Box]
|
||
|
|
position = 32
|
||
|
|
size = 108
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
creation_time = UTC 2014/12/12, 18:41:19
|
||
|
|
modification_time = UTC 2014/12/12, 18:41:19
|
||
|
|
timescale = 48000
|
||
|
|
duration = 33600 (00:00:00.700)
|
||
|
|
rate = 1.000000
|
||
|
|
volume = 1.000000
|
||
|
|
reserved = 0x0000
|
||
|
|
reserved = 0x00000000
|
||
|
|
reserved = 0x00000000
|
||
|
|
transformation matrix
|
||
|
|
| a, b, u | | 1.000000, 0.000000, 0.000000 |
|
||
|
|
| c, d, v | = | 0.000000, 1.000000, 0.000000 |
|
||
|
|
| x, y, w | | 0.000000, 0.000000, 1.000000 |
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
next_track_ID = 2
|
||
|
|
[trak: Track Box]
|
||
|
|
position = 140
|
||
|
|
size = 608
|
||
|
|
[tkhd: Track Header Box]
|
||
|
|
position = 148
|
||
|
|
size = 92
|
||
|
|
version = 0
|
||
|
|
flags = 0x000007
|
||
|
|
Track enabled
|
||
|
|
Track in movie
|
||
|
|
Track in preview
|
||
|
|
creation_time = UTC 2014/12/12, 18:41:19
|
||
|
|
modification_time = UTC 2014/12/12, 18:41:19
|
||
|
|
track_ID = 1
|
||
|
|
reserved = 0x00000000
|
||
|
|
duration = 33600 (00:00:00.700)
|
||
|
|
reserved = 0x00000000
|
||
|
|
reserved = 0x00000000
|
||
|
|
layer = 0
|
||
|
|
alternate_group = 0
|
||
|
|
volume = 1.000000
|
||
|
|
reserved = 0x0000
|
||
|
|
transformation matrix
|
||
|
|
| a, b, u | | 1.000000, 0.000000, 0.000000 |
|
||
|
|
| c, d, v | = | 0.000000, 1.000000, 0.000000 |
|
||
|
|
| x, y, w | | 0.000000, 0.000000, 1.000000 |
|
||
|
|
width = 0.000000
|
||
|
|
height = 0.000000
|
||
|
|
[edts: Edit Box]
|
||
|
|
position = 240
|
||
|
|
size = 36
|
||
|
|
[elst: Edit List Box]
|
||
|
|
position = 281
|
||
|
|
size = 28
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 1
|
||
|
|
entry[0]
|
||
|
|
segment_duration = 33600
|
||
|
|
media_time = 312
|
||
|
|
media_rate = 1.000000
|
||
|
|
[mdia: Media Box]
|
||
|
|
position = 276
|
||
|
|
size = 472
|
||
|
|
[mdhd: Media Header Box]
|
||
|
|
position = 284
|
||
|
|
size = 32
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
creation_time = UTC 2014/12/12, 18:41:19
|
||
|
|
modification_time = UTC 2014/12/12, 18:41:19
|
||
|
|
timescale = 48000
|
||
|
|
duration = 34560 (00:00:00.720)
|
||
|
|
language = und
|
||
|
|
pre_defined = 0x0000
|
||
|
|
[hdlr: Handler Reference Box]
|
||
|
|
position = 316
|
||
|
|
size = 51
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
pre_defined = 0x00000000
|
||
|
|
handler_type = soun
|
||
|
|
reserved = 0x00000000
|
||
|
|
reserved = 0x00000000
|
||
|
|
reserved = 0x00000000
|
||
|
|
name = Xiph Audio Handler
|
||
|
|
[minf: Media Information Box]
|
||
|
|
position = 367
|
||
|
|
size = 381
|
||
|
|
[smhd: Sound Media Header Box]
|
||
|
|
position = 375
|
||
|
|
size = 16
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
balance = 0.000000
|
||
|
|
reserved = 0x0000
|
||
|
|
[dinf: Data Information Box]
|
||
|
|
position = 391
|
||
|
|
size = 36
|
||
|
|
[dref: Data Reference Box]
|
||
|
|
position = 399
|
||
|
|
size = 28
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 1
|
||
|
|
[url : Data Entry Url Box]
|
||
|
|
position = 415
|
||
|
|
size = 12
|
||
|
|
version = 0
|
||
|
|
flags = 0x000001
|
||
|
|
location = in the same file
|
||
|
|
[stbl: Sample Table Box]
|
||
|
|
position = 427
|
||
|
|
size = 321
|
||
|
|
[stsd: Sample Description Box]
|
||
|
|
position = 435
|
||
|
|
size = 79
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 1
|
||
|
|
[Opus: Audio Description]
|
||
|
|
position = 451
|
||
|
|
size = 63
|
||
|
|
reserved = 0x000000000000
|
||
|
|
data_reference_index = 1
|
||
|
|
reserved = 0x0000
|
||
|
|
reserved = 0x0000
|
||
|
|
reserved = 0x00000000
|
||
|
|
channelcount = 6
|
||
|
|
samplesize = 16
|
||
|
|
pre_defined = 0
|
||
|
|
reserved = 0
|
||
|
|
samplerate = 48000.000000
|
||
|
|
[dOps: Opus Specific Box]
|
||
|
|
position = 487
|
||
|
|
size = 27
|
||
|
|
Version = 0
|
||
|
|
OutputChannelCount = 6
|
||
|
|
PreSkip = 312
|
||
|
|
InputSampleRate = 48000
|
||
|
|
OutputGain = 0
|
||
|
|
ChannelMappingFamily = 1
|
||
|
|
StreamCount = 4
|
||
|
|
CoupledCount = 2
|
||
|
|
ChannelMapping
|
||
|
|
0 -> 0: front left
|
||
|
|
1 -> 4: fron center
|
||
|
|
2 -> 1: front right
|
||
|
|
3 -> 2: side left
|
||
|
|
4 -> 3: side right
|
||
|
|
5 -> 5: rear center
|
||
|
|
[stts: Decoding Time to Sample Box]
|
||
|
|
position = 514
|
||
|
|
size = 24
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 1
|
||
|
|
entry[0]
|
||
|
|
sample_count = 18
|
||
|
|
sample_delta = 1920
|
||
|
|
[stsc: Sample To Chunk Box]
|
||
|
|
position = 538
|
||
|
|
size = 40
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 2
|
||
|
|
entry[0]
|
||
|
|
first_chunk = 1
|
||
|
|
samples_per_chunk = 13
|
||
|
|
sample_description_index = 1
|
||
|
|
entry[1]
|
||
|
|
first_chunk = 2
|
||
|
|
samples_per_chunk = 5
|
||
|
|
sample_description_index = 1
|
||
|
|
[stsz: Sample Size Box]
|
||
|
|
position = 578
|
||
|
|
size = 92
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
sample_size = 0 (variable)
|
||
|
|
sample_count = 18
|
||
|
|
entry_size[0] = 977
|
||
|
|
entry_size[1] = 938
|
||
|
|
entry_size[2] = 939
|
||
|
|
entry_size[3] = 938
|
||
|
|
entry_size[4] = 934
|
||
|
|
entry_size[5] = 945
|
||
|
|
entry_size[6] = 948
|
||
|
|
entry_size[7] = 956
|
||
|
|
entry_size[8] = 955
|
||
|
|
entry_size[9] = 930
|
||
|
|
entry_size[10] = 933
|
||
|
|
entry_size[11] = 934
|
||
|
|
entry_size[12] = 972
|
||
|
|
entry_size[13] = 977
|
||
|
|
entry_size[14] = 958
|
||
|
|
entry_size[15] = 949
|
||
|
|
entry_size[16] = 962
|
||
|
|
entry_size[17] = 848
|
||
|
|
[stco: Chunk Offset Box]
|
||
|
|
position = 670
|
||
|
|
size = 24
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
entry_count = 2
|
||
|
|
chunk_offset[0] = 797
|
||
|
|
chunk_offset[1] = 13096
|
||
|
|
[sgpd: Sample Group Description Box]
|
||
|
|
position = 694
|
||
|
|
size = 26
|
||
|
|
version = 1
|
||
|
|
flags = 0x000000
|
||
|
|
grouping_type = roll
|
||
|
|
default_length = 2 (constant)
|
||
|
|
entry_count = 1
|
||
|
|
roll_distance[0] = -2
|
||
|
|
[sbgp: Sample to Group Box]
|
||
|
|
position = 720
|
||
|
|
size = 28
|
||
|
|
version = 0
|
||
|
|
flags = 0x000000
|
||
|
|
grouping_type = roll
|
||
|
|
entry_count = 1
|
||
|
|
entry[0]
|
||
|
|
sample_count = 18
|
||
|
|
group_description_index = 1
|
||
|
|
[free: Free Space Box]
|
||
|
|
position = 748
|
||
|
|
size = 8
|
||
|
|
[mdat: Media Data Box]
|
||
|
|
position = 756
|
||
|
|
size = 17001
|
||
|
|
<a name="5"></a>
|
||
|
|
5 Authors' Address
|
||
|
|
Yusuke Nakamura
|
||
|
|
Email: muken.the.vfrmaniac |at| gmail.com
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|