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| <b><u>Encapsulation of Opus in ISO Base Media File Format</u></b><br> |
| <font size="2">last updated: October 1, 2014</font><br> |
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| Encapsulation of Opus in ISO Base Media File Format |
| Version 0.5.3 (incomplete) |
| |
| |
| 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="#4.4.3">4.4.3</a> Sub-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> Channel Layout |
| <a href="#4.8">4.8</a> Additional Requirements, Restrictions, Recommendations and Definitions for Boxes |
| <a href="#4.8.1">4.8.1</a> File Type Box |
| <a href="#4.8.2">4.8.2</a> Segment Type Box |
| <a href="#4.8.3">4.8.3</a> Movie Header Box |
| <a href="#4.8.4">4.8.4</a> Track Header Box |
| <a href="#4.8.5">4.8.5</a> Edit Box |
| <a href="#4.8.6">4.8.6</a> Edit List Box |
| <a href="#4.8.7">4.8.7</a> Media Header Box |
| <a href="#4.8.8">4.8.8</a> Handler Reference Box |
| <a href="#4.8.9">4.8.9</a> Sound Media Header Box |
| <a href="#4.8.10">4.8.10</a> Sample Table Box |
| <a href="#4.8.11">4.8.11</a> OpusSampleEntry |
| <a href="#4.8.12">4.8.12</a> Opus Specific Box |
| <a href="#4.8.13">4.8.13</a> Sample Group Description Box |
| <a href="#4.8.14">4.8.14</a> Sample to Group Box |
| <a href="#4.8.15">4.8.15</a> Track Extends Box |
| <a href="#4.8.16">4.8.16</a> Track Fragment Box |
| <a href="#4.8.17">4.8.17</a> Track Fragment Header Box |
| <a href="#4.8.18">4.8.18</a> Track Fragment Run Box |
| <a href="#4.9">4.9</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 active track |
| enabled track from the non-alternate group or selected track from alternate group |
| TODO: For alternate group, how about handling of disabled tracks? |
| Some implementations treat disabled tracks in alternate group as a non-default track. |
| Under the such implementations, the selected track behaves as an enabled track. |
| Should we define the implementation in this specification? |
| Or leave it as implementation-defined? |
| |
| 3.2 actual duration |
| duration constructed from valid samples |
| |
| 3.3 edit |
| entry in the Edit List Box |
| |
| 3.4 padded samples |
| PCM samples after decoding Opus sample(s) which are not valid samples |
| An Opus bitstream always contains them partially at the beginning and may contain them in part at the end, as |
| long as not physically removed yet at the beginning and/or the end. |
| |
| 3.5 priming samples |
| padded samples at the beginning of the Opus bitstream |
| |
| 3.6 sample-accurate |
| for any PCM sample, a timestamp exactly matching its sampling timestamp is present in the media timeline. |
| |
| 3.7 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 any brand 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 bitstreams without other derived file formats. |
| It is not preferable that encapsulation of Opus bitstreams with only the brands of the ISO Base Media File |
| Format, though files conformant to this specification are compatible with certain versions of the ISO |
| Base Media File Format. See ISO/IEC 14496-12 [3] E.1 Introduction. |
| If you desire that this file format is an alternative file format to the Ogg Opus, I recommend you define. |
| <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 | |
| +----+----+----+----+----+----+----+----+------------------------------+ |
| |
| Figure 1 - 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 some boxes listed above, the additional requirements, restrictions, recommendations and definitions |
| are specified in 4.8 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 | |
| +----+----+----+----+----+----+----+----+------------------------------+ |
| |
| Figure 2 - 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 some boxes listed above, the additional requirements, restrictions, recommendations and definitions |
| are specified in 4.8 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. |
| All Opus samples are processed byte-by-byte. Therefore, the endianness has nothing to do with any Opus sample. |
| <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 for each of different Opus bitstreams. Due to support more than |
| two channels, an Opus sample can contain frames from multiple Opus bitstreams but all Opus packets shall |
| share with the total of frame sizes in a single Opus sample. The way of how to pack an Opus packet from |
| each of Opus bitstreams into a single Opus sample follows Appendix B. in RFC 6716 [3]. |
| 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]. |
| |
| +-----------------------------------------+-------------------------------------+ |
| | Opus packet 0 (self-delimiting framing) | Opus packet 1 (undelimited framing) | |
| +-----------------------------------------+-------------------------------------+ |
| |<---------------------------- the size of Opus sample ------------------------>| |
| |
| Figure 3 - Example structure of an Opus sample containing two Opus bitstreams |
| |
| 4.4.2 Duration of Opus sample<a name="4.4.2"></a> |
| The duration of Opus sample is given by multiplying the total of frame sizes for a single Opus bitstream |
| expressed in seconds by the value of the timescale field in the Media Header Box. |
| Let's say an Opus sample consists of two Opus bitstreams, where the frame size of one bitstream is 40 milli- |
| seconds and the frame size of another is 60 milliseconds, and the timescale field in the Media Header Box |
| is set to 48000, then the duration of that Opus sample shall be 120 milliseconds since three 40 millisecond |
| frame and two 60 millisecond frames shall be contained because of the maximum duration of Opus packet, 120 |
| milliseconds, and 5760 in the timescale indicated 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. |
| |
| 4.4.3 Sub-sample<a name="4.4.3"></a> |
| The structure of the last Opus packet in an Opus sample is different from the others in the same Opus sample, |
| and the others are invalid Opus packets as an Opus sample because of self-delimiting framing. To avoid |
| complexities, sub-sample is not defined for Opus sample in this specification. |
| <a name="4.5"></a> |
| 4.5 Random Access |
| 4.5.1 Random Access Point<a name="4.5.1"></a> |
| All Opus samples can be independently decoded i.e. every Opus sample is a sync sample. Therefore, the Sync |
| Sample Box shall not be present as long as there are no samples other than Opus samples in the same track. |
| |
| 4.5.2 Pre-roll<a name="4.5.2"></a> |
| Opus requires at least 80 millisecond 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 |
| 4.8.1 File Type Box and 4.8.2 Segment Type Box in this specification. |
| <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 |
| padded samples at the end, we need trim from media to get the actual duration. 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 may contain 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 4.8.6 Edit List Box in this specification. |
| <a name="4.7"></a> |
| 4.7 Channel Layout |
| 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, 1, 2, 3, 4, 5}; // front left, front center, front right, rear left, rear right, LFE |
| 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. |
| |
| TODO: The future amendments of ISO/IEC 14496-12 [1] will add further supports of channel layouts and it may be |
| able to exclude certain channels from the already mapped channels to remove pure silent channels. The |
| channel mapping defined in the Opus Specific Box should be designed as processed before the extensions, |
| and the extensions should be placed after the Opus Specific Box. |
| <a name="4.8"></a> |
| 4.8 Additional Requirements, Restrictions, Recommendations and Definitions for Boxes |
| 4.8.1 File Type Box<a name="4.8.1"></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 the structural |
| boxes listed at 4.2 Basic Structure, and the additional requirements, restrictions, recommendations and |
| definitions specified in 4.8 Additional Requirements, Restrictions, Recommendations and Definitions for |
| Boxes in this specification. |
| As an example, the minimal support of the encapsulation of Opus bitstreams in ISO Base Media file format |
| requires the 'iso2' brand since support of roll groups is required. |
| |
| 4.8.2 Segment Type Box<a name="4.8.2"></a> |
| The same requirements are applied as specified at 4.8.1 File Type Box in this specification. |
| |
| 4.8.3 Movie Header Box<a name="4.8.3"></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. |
| |
| 4.8.4 Track Header Box<a name="4.8.4"></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. |
| |
| 4.8.5 Edit Box<a name="4.8.5"></a> |
| For any track containing Opus bitstreams, exactly one Edit Box shall be present. |
| |
| 4.8.6 Edit List Box<a name="4.8.6"></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 can be 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 |
| field shall be set to the number of the valid samples to indicate the actual duration. |
| 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 |
| the padded samples from the presentation timeline when producing movie fragments on the fly. |
| + media_time: |
| The media_time field can be used to remove the priming samples of Opus bitstreams. |
| When the value of the timescale field in the Media Header Box is equal to 48000, the media_time field |
| shall be set to the number of the priming samples to remove the priming samples. |
| + media_rate: |
| If the segment_duration field is used to indicate the actual duration, the media_rate field shall be |
| set to 1. |
| |
| 4.8.7 Media Header Box<a name="4.8.7"></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. |
| |
| 4.8.8 Handler Reference Box<a name="4.8.8"></a> |
| For any track containing Opus bitstreams, the following requirement is applied. |
| + handler_type: |
| The handler_type field shall be set to 'soun'. |
| |
| 4.8.9 Sound Media Header Box<a name="4.8.9"></a> |
| For any track containing Opus bitstreams, the Sound Media Header Box shall be present. |
| |
| 4.8.10 Sample Table Box<a name="4.8.10"></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 as long as there are |
| no samples other than Opus samples in the same track. |
| |
| 4.8.11 OpusSampleEntry<a name="4.8.11"></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<<16. |
| |
| 4.8.12 Opus Specific Box<a name="4.8.12"></a> |
| Exactly one Opus Specific Box shall be present in each OpusSampleEntry. |
| The Opus Specific Box contains the version field and this specification defines version 0 of this box. |
| If incompatible changes occured in the fields after the version field within the OpusSpecificBox in the |
| future versions of this specification, another version will be defined. |
| |
| The syntax and semantics of the Opus Specific Box is shown as follows. |
| |
| class ChannelMappingTable (unsigned int(8) OutputChannelCount){ |
| unsigned int(8) StreamCount; |
| unsigned int(8) CoupledCount; |
| unsigned int(8 * OutputChannelCount) ChannelMapping; |
| } |
| |
| aligned(8) class OpusSpecificBox extends FullBox('dOps', version, dflags){ |
| unsigned int(8) OutputChannelCount; |
| if (dflags & 0x000001) { |
| unsigned int(16) PreSkip; |
| } |
| if (dflags & 0x000002) { |
| unsigned int(32) InputSampleRate; |
| } |
| if (dflags & 0x000004) { |
| signed int(16) OutputGain; |
| } |
| unsigned int(8) ChannelMappingFamily; |
| if (ChannelMappingFamily != 0) { |
| ChannelMappingTable(OutputChannelCount); |
| } |
| } |
| |
| + version: |
| The version field shall be set to 0. |
| In the future versions of this specification, this field may be set to other values. And without support |
| of those values, the reader shall not read the fields after this within the OpusSpecificBox. |
| + flags: |
| The following flags are defined in the dflags: |
| 0x000001 pre-skip-present: |
| This flag indicates the presence of the PreSkip field. |
| 0x000002 input-sample-rate-present: |
| This flag indicates the presence of the InputSampleRate field. |
| 0x000004 output-gain-present: |
| This flag indicates the presence of the OutputGain field. |
| + 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]. |
| + 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. |
| The PreSkip field can be absent after removing Opus samples containing the number of PCM samples more |
| than of the priming samples. |
| The PreSkip field is not used for removing the priming samples at the whole playback at all since it is |
| informative only, and that task falls on the Edit List Box. |
| + 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. |
| If the InputSampleRate field is absent, process as if it is set to 0, which indicates "unspecified". |
| + 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 8.8 fixed-point and big-endian format. |
| If the OutputGain field is absent, process as if it is set to 0. |
| + 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]. |
| + StreamCount: |
| The StreamCount field shall be set to the same value as the *Stream Count* field in the identification |
| header defined in Ogg Opus [4]. |
| + CoupledCount: |
| The CoupledCount field shall be set to the same value as the *Coupled Count* field in the identification |
| header defined in Ogg Opus [4]. |
| + ChannelMapping: |
| The ChannelMapping field shall be set to the same octet string as *Channel Mapping* field in the identi- |
| fication header defined in Ogg Opus [4]. |
| |
| 4.8.13 Sample Group Description Box<a name="4.8.13"></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'. In addition, the following requirements and restriction are applied. |
| + version: |
| The version field shall be set to 1 if the grouping_type field set to 'roll'. |
| + default_length |
| The default_length field shall be set to 2 if the grouping_type field set to 'roll'. |
| + roll_distance: |
| The roll_distance field in any AudioRollRecoveryEntry shall not be set to zero and positive values for |
| any Opus sample. |
| |
| See also 4.5.2 Pre-roll. |
| |
| 4.8.14 Sample to Group Box<a name="4.8.14"></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'. |
| |
| 4.8.15 Track Extends Box<a name="4.8.15"></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. |
| |
| 4.8.16 Track Fragment Box<a name="4.8.16"></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. |
| |
| 4.8.17 Track Fragment Header Box<a name="4.8.17"></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. |
| |
| 4.8.18 Track Fragment Run Box<a name="4.8.18"></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="4.9"></a> |
| 4.9 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 (00:00:00.700) |
| 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 |
| [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 (00:00:00.700) |
| 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 = 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 (00:00:00.800) |
| 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 = 0x000006 |
| OutputChannelCount = 2 |
| InputSampleRate = 44100 |
| OutputGain = 0.000000 |
| 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> |
