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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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    <head>
        <link rel="stylesheet" type="text/css" href="../style.css"/>
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        <title>Encapsulation of Opus in ISO Base Media File Format</title>
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    <body bgcolor="0x333333" text="#60B0C0">
        <b><u>Encapsulation of Opus in ISO Base Media File Format</u></b><br>
        <font size="2">last updated: September 26, 2014</font><br>
        <br>
        <div class="normal_link pre frame_box">
<center>Encapsulation of Opus in ISO Base Media File Format</center>
<center>Version 0.1.4 (incomplete)</center>

Table of Contents
<a href="#1">1</a> Scope
<a href="#2">2</a> Normative References
<a href="#3">3</a> Terms and Definitions
<a href="#4">4</a> Design Rules of Encapsulation
    <a href="#4.1">4.1</a> File Type Indentification
    <a href="#4.2">4.2</a> Basic Structure
        <a href="#4.2.1">4.2.1</a> Initial Movie
        <a href="#4.2.2">4.2.2</a> Movie Fragments
    <a href="#4.3">4.3</a> Byte Order
    <a href="#4.4">4.4</a> Definition of Opus sample
        <a href="#4.4.1">4.4.1</a> Opus sample
        <a href="#4.4.2">4.4.2</a> Duration of Opus sample
    <a href="#4.5">4.5</a> Random Access
        <a href="#4.5.1">4.5.1</a> Random Access Point
        <a href="#4.5.2">4.5.2</a> Pre-roll
    <a href="#4.6">4.6</a> Trimming of Actual Duration
    <a href="#4.7">4.7</a> Additional Requirements, Restrictions, Recommendations and Definitions for Boxes
        <a href="#4.7.1">4.7.1</a> File Type Box
        <a href="#4.7.2">4.7.2</a> Segment Type Box
        <a href="#4.7.3">4.7.3</a> Movie Header Box
        <a href="#4.7.4">4.7.4</a> Track Header Box
        <a href="#4.7.5">4.7.5</a> Edit Box
        <a href="#4.7.6">4.7.6</a> Edit List Box
        <a href="#4.7.7">4.7.7</a> Media Header Box
        <a href="#4.7.8">4.7.8</a> Handler Reference Box
        <a href="#4.7.9">4.7.9</a> Sound Media Header Box
        <a href="#4.7.10">4.7.10</a> Sample Table Box
        <a href="#4.7.11">4.7.11</a> OpusSampleEntry
        <a href="#4.7.12">4.7.12</a> Opus Specific Box
        <a href="#4.7.13">4.7.13</a> Sample Group Description Box
        <a href="#4.7.14">4.7.14</a> Sample to Group Box
        <a href="#4.7.15">4.7.15</a> Track Extends Box
        <a href="#4.7.16">4.7.16</a> Track Fragment Box
        <a href="#4.7.17">4.7.17</a> Track Fragment Header Box
        <a href="#4.7.18">4.7.18</a> Track Fragment Run Box
    <a href="#4.8">4.8</a> Example of Encapsulation
<a href="#5">5</a> Author's Address

<a name="1"></a>
1 Scope
    This specification specifies the fundamental way of the encapsulation of Opus coded bitstreams in ISO Base Media
    file formats and its derivatives.

<a name="2"></a>
2 Normative References
    [1] ISO/IEC 14496-12:2012 Corrected version
        Information technology — Coding of audio-visual objects — Part 12: ISO base media file format

    [2] ISO/IEC 14496-12:2012/Amd.1:2013
        Information technology — Coding of audio-visual objects — Part 12: ISO base media file format
        AMENDMENT 1: Various enhancements including support for large metadata

    [3] RFC 6716
        Definition of the Opus Audio Codec

    [4] draft-ietf-codec-oggopus-04
        Ogg Encapsulation for the Opus Audio Codec

<a name="3"></a>
3 Terms and Definitions
    3.1 actual duration
        duration constructed from valid samples

    3.2 edit
        entry in the Edit List Box

    3.3 padded samples
        PCM samples after decoding Opus sample(s) which are not valid samples

    3.4 priming samples
        extra PCM samples after decoding Opus sample(s) at the beginning of the Opus bitstream

    3.5 sample-accurate
        for any PCM sample, a timestamp exactly matching its sampling timestamp is present in the media timeline.

    3.6 valid samples
        PCM samples after decoding Opus sample(s) corresponding to input PCM samples

<a name="4"></a>
4 Design Rules of Encapsulation
    4.1 File Type Indentification<a name="4.1"></a>
        This specification does not define brands to declare files are conformant to this specification.
        TODO: Should we define such brands, e.g. 'Opus'. If we define the brand(s), we can utilize files conformant to
              this specification for the storage of Opus coded bitstream without other derived file formats.
<a name="4.2"></a>
    4.2 Basic Structure
        4.2.1 Initial Movie<a name="4.2.1"></a>
            This subclause specifies 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 Information 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            |
            +----+----+----+----+----+----+----+----+------------------------------+

            It is strongly recommended that the order of boxes should follow the above structure.
            Boxes marked with an asterisk (*) may be present.
            For some boxes listed above, the additional requirements, restrictions, recommendations and definitions
            are specified in 4.7 Additional Requirements, Restrictions, Recommendations and Definitions for Boxes in
            this specification.
            For the others, the definition is as is defined in ISO/IEC 14496-12 [1].

        4.2.2 Movie Fragments<a name="4.2.2"></a>
            This subclause specifies 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          |
            +----+----+----+----+----+----+----+----+------------------------------+

            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 some boxes listed above, the additional requirements, restrictions, recommendations and definitions
            are specified in 4.7 Additional Requirements, Restrictions, Recommendations and Definitions for Boxes in
            this specification.
            For the others, the definition is as is defined in ISO/IEC 14496-12 [1].
<a name="4.3"></a>
    4.3 Byte Order
        The fields in the boxes are stored as big-endian format.
        TODO: What about bytes in Opus samples?
<a name="4.4"></a>
    4.4 Definition of Opus sample
        4.4.1 Opus sample<a name="4.4.1"></a>
            An Opus sample is exactly one Opus packet.
            In this specification, 'sample' means 'Opus sample' except for 'padded samples', 'priming samples', 'valid
            sample' and 'sample-accurate', i.e. 'sample' is 'sample' in the term defined in ISO/IEC 14496-12 [1].
            TODO: If an Opus packet consists of multiple Opus streams, it can be splitted into individual streams and
                  reconstructed into new Opus packets as long as every Opus stream has the same total duration in each
                  Opus packet. This requires additional channel mapping at outside of the existing Opus Specific Box.
                  The solution may be achieved by using track references and new channel mapping/layout indications.
                  Or should we forbid splitting into multiple tracks to avoid more complex implementations?
                  Or just use channel mapping other than what the existing Opus Specific Box does, such as bit masks?

        4.4.2 Duration of Opus sample<a name="4.4.2"></a>
            The duration of Opus sample is given by multiplying the least common multiple of the frame size in seconds
            of all frames inside Opus packet by the value of the timescale field in the Media Header Box.

            To indicate the valid samples excluding the padded samples at the end of Opus bitstream, the duration of
            the last Opus sample of an Opus bitstream is given by multiplying the number of the valid samples by the
            value produced by dividing the value of the timescale field in the Media Header Box by 48000.
<a name="4.5"></a>
    4.5 Random Access
        4.5.1 Random Access Point<a name="4.5.1"></a>
            All Opus packets can be independently decoded i.e. every Opus sample is a sync sample.
            Therefore, the Sync Sample Box shall not be present.

        4.5.2 Pre-roll<a name="4.5.2"></a>
            Opus requires at least 80 milli-second pre-roll after each random access.
            Pre-roll is indicated by the roll_distance field in AudioRollRecoveryEntry. AudioPreRollEntry shall not be
            used since every Opus sample is a sync sample in Opus bitstream.
            Note that roll_distance is expressed in sample units in a term of ISO Base Media File Format, and always
            takes negative values.

            For the requirement of AudioRollRecoveryEntry, the compatible_brands field in the File Type Box and/or
            the Segment Type Box shall contain at least one brand which requires support for roll groups.
            See also 4.7.1 File Type Box and 4.7.2 Segment Type Box.
<a name="4.6"></a>
    4.6 Trimming of Actual Duration
        Due to the priming samples (or the padding at the beginning) derived from the pre-roll for the startup and the
        padding at the end, we need trim from media to get the actual duration before encoded.
        An edit in the Edit List Box can achieve this demand.
        For sample-accurate trimming, proper timescale should be set to the timescale field in the Movie Header Box
        and the Media Header Box inside Track Box(es) for Opus bitstream.

        The Edit List Box is applied to whole movie including all movie fragments. Therefore, it is impossible to tell
        the actual duration in the case producing movie fragments on the fly such as live-streaming. In such cases,
        the duration of the last Opus sample may be helpful.
        TODO: Should we define a new box which indicates the last Opus samples?
              Since this specification allows multiple sample descriptions, i.e. allows concatenation of multiple Opus
              bitstreams in a track, each Opus bitstream contains some padded samples.
              Without such a box, we cannot know in container level whether an Opus sample is the last Opus sample in
              an Opus bitstream or not. Is this preferable?

        See also 4.7.6 Edit List Box.
<a name="4.7"></a>
    4.7 Additional Requirements, Restrictions, Recommendations and Definitions for Boxes
        4.7.1 File Type Box<a name="4.7.1"></a>
            For any track containing Opus bitstreams, the following requirements are applied.
            + compatible_brands:
                The compatible_brands fields shall contain at least one brand which requires support for roll groups
                (e.g. the 'iso2' brand).
                When enabling movie fragments and placing at least one Sample Group Description Box in Movie Fragments,
                the compatible_brands fields shall also contain at least one brand which requires support of Sample
                Group Description Boxes in Movie Fragments (e.g. the 'iso6' brand).

        4.7.2 Segment Type Box<a name="4.7.2"></a>
            For any track containing Opus bitstreams, the following requirements are applied.
            + compatible_brands:
                The same requirements as specified at 4.7.1 File Type Box are applied.

        4.7.3 Movie Header Box<a name="4.7.3"></a>
            If any track containing Opus bitstreams, the following recommendations are applied.
            + timescale:
                The timescale field should be set to the same value of the timescale field in the Media Header Box
                inside Track Box(es) for Opus bitstream if no tracks for bitstreams other than Opus bitstream is present.

        4.7.4 Track Header Box<a name="4.7.4"></a>
            For any track containing Opus bitstreams, the following requirements are applied.
            + layer:
                The layer field shall be set to 0.
            + matrix:
                The matrix field shall be set to { 0x00010000,0,0,0,0x00010000,0,0,0,0x40000000 }.
            + width:
                The width field shall be set to 0.
            + height:
                The height field shall be set to 0.

        4.7.5 Edit Box<a name="4.7.5"></a>
            For any track containing Opus bitstreams, exactly one Edit Box shall be present.

        4.7.6 Edit List Box<a name="4.7.6"></a>
            For any track containing Opus bitstreams, exactly one Edit List Box shall be present. In addition, for
            non-empty edits, the following recommendations are applied.
            + segment_duration:
                The segment_duration field is used to indicate the actual duration of Opus bitstream.
                When the value of the timescale field in the Movie Header Box is equal to 48000, the segment_duration
                should be set to the number of the actual samples before encoded.
                When enabling movie fragments, the segment_duration field may be set to 0. The value 0 represents
                implicit duration equal to the sum of the duration of all samples. This would be helpful for excluding
                padded samples from the presentation timeline when producing movie fragments on the fly.
            + media_time:
                The media_time field is used to remove the priming samples of Opus bitstream.
                When the value of the timescale field in the Media Header Box is equal to 48000, the media_time shall
                be set to the number of priming samples to remove the priming samples for the first non-empty edit.

        4.7.7 Media Header Box<a name="4.7.7"></a>
            For any track containing Opus bitstreams, the following recommendation is applied.
            + timescale:
                The timescale field should be set to 48000 to access sample-accurately.

        4.7.8 Handler Reference Box<a name="4.7.8"></a>
            For any track containing Opus bitstreams, the following requirement is applied.
            + handler_type:
                The handler_type field shall be set to 'soun'.

        4.7.9 Sound Media Header Box<a name="4.7.9"></a>
            For any track containing Opus bitstreams, the Sound Media Header Box shall be present.

        4.7.10 Sample Table Box<a name="4.7.10"></a>
            For any track containing Opus bitstreams, at least one Sample Group Description Boxes and at least one
            Sample to Group Boxes shall be present and the Sync Sample Box shall not be present.

        4.7.11 OpusSampleEntry<a name="4.7.11"></a>
            For any track containing Opus bitstreams, at least one OpusSampleEntry shall be present.

            The syntax and semantics of the OpusSampleEntry is shown as follows.

            class OpusSampleEntry() extends AudioSampleEntry ('Opus'){
                OpusSpecificBox();
            }

            + channelcount:
                The channelcount field shall be set to the sum of the total number of Opus bitstreams and the number
                of Opus bitstreams producing two channels. This value is indentical with (M+N), where M is the value of
                the *Coupled Stream Count* field and N is the value of the *Stream Count* field in the *Channel Mapping
                Table* in the identification header defined in Ogg Opus [4].
            + samplesize:
                The samplesize field shall be set to 16.
            + samplerate:
                The samplerate field shall be set to 48000&lt&lt16.

        4.7.12 Opus Specific Box<a name="4.7.12"></a>
            Exactly one Opus Specific Box shall be present in each OpusSampleEntry.

            The syntax and semantics of the Opus Specific Box is shown as follows.

            aligned(8) class OpusSpecificBox extends FullBox('dOps', version, dflags){
                if (flags & 0x000001) {
                    unsigned int(16) PreSkip;
                }
                unsigned int(32) InputSampleRate;
                signed int(16)   OutputGain;
                unsigned int(8)  OutputChannelCount;
                unsigned int(8)  ChannelMappingFamily;
                if (ChannelMappingFamily != 0) {
                    unsigned int(8 * (2 + OutputChannelCount)) ChannelMappingTable;
                }
            }

            + version:
                The version field shall be set to 0.
            + flags:
                The following flags are defined in the dflags:
                    0x000001 pre-skip-present:
                        This flag indicates the presence of the PreSkip field.
            + PreSkip:
                The PreSkip field shall be set to the same value as the *Pre-skip* field in the identification header
                defined in Ogg Opus [4]. Note that the value is stored as big-endian format.
                This field can be absent after removing Opus samples containing the number of PCM samples more than the
                number of the priming samples.
                This field is not used for removing the priming samples at playback.
            + InputSampleRate:
                The InputSampleRate field shall be set to the same value as the *Input Sample Rate* field in the
                identification header defined in Ogg Opus [4]. Note that the value is stored as big-endian format.
            + OutputGain:
                The OutputGain field shall be set to the same value as the *Output Gain* field in the identification
                header define in Ogg Opus [4]. Note that the value is stored as big-endian format.
            + OutputChannelCount:
                The OutputChannelCount field shall be set to the same value as the *Output Channel Count* field in the
                identification header defined in Ogg Opus [4].
            + ChannelMappingFamily:
                The ChannelMappingFamily field shall be set to the same value as the *Channel Mapping Family* field in
                the identification header defined in Ogg Opus [4].
            + ChannelMappingTable:
                The ChannelMappingTable field shall be set to the same octet string as *Channel Mapping Table* field in
                the identification header defined in Ogg Opus [4].

        4.7.13 Sample Group Description Box<a name="4.7.13"></a>
            For any track containing Opus bitstreams, at least one Sample Group Description Box shall be present and have
            the grouping_type field set to 'roll'. See also 4.5.2 Pre-roll.

        4.7.14 Sample to Group Box<a name="4.7.14"></a>
            For any track containing Opus bitstreams, at least one Sample to Group Box shall be present and have the
            grouping_type field set to 'roll'. In addition, the following requirement is applied.
            + group_description_index:
                The group_description_index fields shall not be set to 0 if the grouping_type field set to 'roll'.

        4.7.15 Track Extends Box<a name="4.7.15"></a>
            For any track containing Opus bitstreams, the following requirement is applied.
            + default_sample_flags:
                The sample_is_non_sync_sample field shall be set to 0.

        4.7.16 Track Fragment Box<a name="4.7.16"></a>
            For any track containing Opus bitstreams, if any sample is contained in track fragment, the Sample to
            Group Box with the grouping_type field set to 'roll' shall be present for that track fragment.

        4.7.17 Track Fragment Header Box<a name="4.7.17"></a>
            For any track containing Opus bitstreams, the following requirement is applied.
            + default_sample_flags:
                The sample_is_non_sync_sample field shall be set to 0.

        4.7.18 Track Fragment Run Box<a name="4.7.18"></a>
            For any track containing Opus bitstreams, the following requirements are applied.
            + first_sample_flags:
                The sample_is_non_sync_sample field shall be set to 0.
            + sample_flags:
                The sample_is_non_sync_sample field shall be set to 0.
<a name="4.8"></a>
    4.8 Example of Encapsulation
        [File]
            size = 10349
            [ftyp: File Type Box]
                position = 0
                size = 24
                major_brand = mp42 : MP4 version 2
                minor_version = 0
                compatible_brands
                    brand[0] = mp42 : MP4 version 2
                    brand[1] = iso2 : ISO Base Media file format version 2
            [free: Free Space Box]
                position = 24
                size = 8
            [mdat: Media Data Box]
                position = 32
                size = 9551
            [moov: Movie Box]
                position = 9583
                size = 766
                [mvhd: Movie Header Box]
                    position = 9591
                    size = 108
                    version = 0
                    flags = 0x000000
                    creation_time = UTC 2014/09/23, 15:23:21
                    modification_time = UTC 2014/09/23, 15:23:21
                    timescale = 48000
                    duration = 33600 (00:00:07.000)
                    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
                [iods: Object Descriptor Box]
                    position = 9699
                    size = 33
                    version = 0
                    flags = 0x000000
                    [tag = 0x10: MP4_IOD]
                        expandableClassSize = 16
                        ObjectDescriptorID = 1
                        URL_Flag = 0
                        includeInlineProfileLevelFlag = 0
                        reserved = 0xf
                        ODProfileLevelIndication = 0xff
                        sceneProfileLevelIndication = 0xff
                        audioProfileLevelIndication = 0xfe
                        visualProfileLevelIndication = 0xff
                        graphicsProfileLevelIndication = 0xff
                        [tag = 0x0e: ES_ID_Inc]
                            expandableClassSize = 4
                            Track_ID = 1
                [trak: Track Box]
                    position = 9732
                    size = 617
                    [tkhd: Track Header Box]
                        position = 9740
                        size = 92
                        version = 0
                        flags = 0x000007
                            Track enabled
                            Track in movie
                            Track in preview
                        creation_time = UTC 2014/09/23, 15:23:21
                        modification_time = UTC 2014/09/23, 15:23:21
                        track_ID = 1
                        reserved = 0x00000000
                        duration = 33600 (00:00:07.000)
                        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 = 9832
                        size = 36
                        [elst: Edit List Box]
                            position = 9840
                            size = 28
                            version = 0
                            flags = 0x000000
                            entry_count = 1
                            entry[0]
                                segment_duration = 33600
                                media_time = 3840
                                media_rate = 1.000000
                    [mdia: Media Box]
                        position = 9868
                        size = 481
                        [mdhd: Media Header Box]
                            position = 9876
                            size = 32
                            version = 0
                            flags = 0x000000
                            creation_time = UTC 2014/09/23, 15:23:21
                            modification_time = UTC 2014/09/23, 15:23:21
                            timescale = 48000
                            duration = 38400 (00:00:08.000)
                            language = und
                            pre_defined = 0x0000
                        [hdlr: Handler Reference Box]
                            position = 9908
                            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 = 9959
                            size = 390
                            [smhd: Sound Media Header Box]
                                position = 9967
                                size = 16
                                version = 0
                                flags = 0x000000
                                balance = 0.000000
                                reserved = 0x0000
                            [dinf: Data Information Box]
                                position = 9983
                                size = 36
                                [dref: Data Reference Box]
                                    position = 9991
                                    size = 28
                                    version = 0
                                    flags = 0x000000
                                    entry_count = 1
                                    [url : Data Entry Url Box]
                                        position = 10007
                                        size = 12
                                        version = 0
                                        flags = 0x000001
                                        location = in the same file
                            [stbl: Sample Table Box]
                                position = 10019
                                size = 330
                                [stsd: Sample Description Box]
                                    position = 10027
                                    size = 72
                                    version = 0
                                    flags = 0x000000
                                    entry_count = 1
                                    [Opus: Audio Description]
                                        position = 10043
                                        size = 56
                                        reserved = 0x000000000000
                                        data_reference_index = 1
                                        reserved = 0x0000
                                        reserved = 0x0000
                                        reserved = 0x00000000
                                        channelcount = 2
                                        samplesize = 16
                                        pre_defined = 0
                                        reserved = 0
                                        samplerate = 48000.000000
                                        [dOps: Opus Specific Box]
                                            position = 10071
                                            size = 20
                                            version = 0
                                            flags = 0x000000
                                            InputSampleRate = 44100
                                            OutputGain = 0.000000
                                            OutputChannelCount = 2
                                            ChannelMappingFamily = 0
                                [stts: Decoding Time to Sample Box]
                                    position = 10099
                                    size = 24
                                    version = 0
                                    flags = 0x000000
                                    entry_count = 1
                                    entry[0]
                                        sample_count = 10
                                        sample_delta = 3840
                                [stsc: Sample To Chunk Box]
                                    position = 10123
                                    size = 40
                                    version = 0
                                    flags = 0x000000
                                    entry_count = 2
                                    entry[0]
                                        first_chunk = 1
                                        samples_per_chunk = 4
                                        sample_description_index = 1
                                    entry[1]
                                        first_chunk = 3
                                        samples_per_chunk = 2
                                        sample_description_index = 1
                                [stsz: Sample Size Box]
                                    position = 10163
                                    size = 60
                                    version = 0
                                    flags = 0x000000
                                    sample_size = 0 (variable)
                                    sample_count = 10
                                    entry_size[0] = 780
                                    entry_size[1] = 920
                                    entry_size[2] = 963
                                    entry_size[3] = 988
                                    entry_size[4] = 1024
                                    entry_size[5] = 951
                                    entry_size[6] = 933
                                    entry_size[7] = 1017
                                    entry_size[8] = 992
                                    entry_size[9] = 975
                                [stco: Chunk Offset Box]
                                    position = 10223
                                    size = 28
                                    version = 0
                                    flags = 0x000000
                                    entry_count = 3
                                    chunk_offset[0] = 40
                                    chunk_offset[1] = 3691
                                    chunk_offset[2] = 7616
                                [sgpd: Sample Group Description Box]
                                    position = 10251
                                    size = 30
                                    version = 1
                                    flags = 0x000000
                                    grouping_type = roll
                                    default_length = 2 (constant)
                                    entry_count = 3
                                    roll_distance[0] = -1
                                    roll_distance[1] = -2
                                    roll_distance[2] = -3
                                [sbgp: Sample to Group Box]
                                    position = 10281
                                    size = 68
                                    version = 0
                                    flags = 0x000000
                                    grouping_type = roll
                                    entry_count = 6
                                    entry[0]
                                        sample_count = 2
                                        group_description_index = 1
                                    entry[1]
                                        sample_count = 1
                                        group_description_index = 2
                                    entry[2]
                                        sample_count = 1
                                        group_description_index = 3
                                    entry[3]
                                        sample_count = 1
                                        group_description_index = 2
                                    entry[4]
                                        sample_count = 3
                                        group_description_index = 3
                                    entry[5]
                                        sample_count = 2
                                        group_description_index = 1

<a name="5"></a>
5 Authors' Address
    Yusuke Nakamura
        Email: muken.the.vfrmaniac |at| gmail.com
        </div>
    </body>
</html>