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| <pre class='metadata'> | ||
| Group: AOM | ||
| Status: FD | ||
| Text Macro: SPECVERSION v1.0.0 | ||
| Title: Carriage of ID3 Timed Metadata in the Common Media Application Format (CMAF) | ||
| Status: PD | ||
| Text Macro: SPECVERSION v1.1.0 | ||
| Date: 2020-03-12 | ||
| Editor: TBD | ||
| Editor: TBD | ||
| Abstract: This specification defines how ID3 metadata can be carried as timed metadata in Common Media Application Format (CMAF) compatible fragmented MP4 streams using Event Message (emsg) boxes. | ||
| URL: https://AOMediaCodec.github.io/id3-emsg | ||
| Shortname: id3-esmg | ||
| Editor: Krasimir Kolarov, [email protected]; | ||
| Editor: John Simmons, [email protected] | ||
| Abstract: This specification defines how ID3 metadata can be carried as timed metadata in Common Media Application Format (CMAF) compatible fragmented MP4 streams using Event Message ('emsg') boxes. | ||
| Date: 2020-03-12 | ||
| Group: AOM | ||
| Repository: AOMediaCodec/id3-esmg | ||
| Inline Github Issues: full | ||
| Boilerplate: property-index no, issues-index no, copyright yes | ||
| Markup Shorthands: css no | ||
| !Previously approved version: <a href="v1.0.0.html">https://aomediacodec.github.io/id3-emsg/v1.0.0.html</a> | ||
| !Latest approved version: <a href="latest-approved.html">https://aomediacodec.github.io/id3-emsg/latest-approved.html</a> | ||
| !Latest draft version: <a href="latest-draft.html">https://aomediacodec.github.io/id3-emsg/latest-draft.html</a> | ||
| Metadata Order: This version, !*, * | ||
| </pre> | ||
|
|
||
| <pre class='biblio'> | ||
| { | ||
| "HLS": { | ||
| "href": "https://tools.ietf.org/html/rfc8216", | ||
| "id": "HLS", | ||
| "title": "HTTP Live Streaming", | ||
| "status": "Standard", | ||
| "publisher": "IETF" | ||
| }, | ||
| "CMAF": { | ||
| "href": "http://www.iso.org/iso/catalogue_detail?csnumber=71975", | ||
| "id": "CMAF", | ||
| "title": "Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media", | ||
| "status": "Standard", | ||
| "publisher": "ISO" | ||
| }, | ||
| "ID3": { | ||
| "href": "http://www.id3.org/Developer_Information", | ||
| "id": "ID3", | ||
| "title": "The ID3 audio file data tagging format", | ||
| "status": "Standard", | ||
| "publisher": "ID3.org" | ||
| }, | ||
| "TM-HLS": { | ||
| "href": "https://developer.apple.com/library/archive/documentation/AudioVideo/Conceptual/HTTP_Live_Streaming_Metadata_Spec/Introduction/Introduction.html", | ||
| "id": "TM-HLS", | ||
| "title": "Timed Metadata for HTTP Live Streaming", | ||
| "status": "Documentation", | ||
| "publisher": "Apple" | ||
| }, | ||
| "DASH": { | ||
| "href": "https://www.iso.org/standard/65274.html", | ||
| "id": "DASH", | ||
| "title": "Information technology — Dynamic adaptive streaming over HTTP (DASH) — Part 1: Media presentation description and segment formats", | ||
| "status": "Standard", | ||
| "publisher": "ISO" | ||
| } | ||
| "HLS": { | ||
| "href": "https://tools.ietf.org/html/rfc8216", | ||
| "id": "HLS", | ||
| "title": "HTTP Live Streaming", | ||
| "status": "Standard", | ||
| "publisher": "IETF" | ||
| }, | ||
| "CMAF": { | ||
| "href": "http://www.iso.org/iso/catalogue_detail?csnumber=71975", | ||
| "id": "CMAF", | ||
| "title": "Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media", | ||
| "status": "Standard", | ||
| "publisher": "ISO" | ||
| }, | ||
| "ID3": { | ||
| "href": "http://www.id3.org/Developer_Information", | ||
| "id": "ID3", | ||
| "title": "The ID3 audio file data tagging format", | ||
| "status": "Standard", | ||
| "publisher": "ID3.org" | ||
| }, | ||
| "TM-HLS": { | ||
| "href": "https://developer.apple.com/library/archive/documentation/AudioVideo/Conceptual/HTTP_Live_Streaming_Metadata_Spec/Introduction/Introduction.html", | ||
| "id": "TM-HLS", | ||
| "title": "Timed Metadata for HTTP Live Streaming", | ||
| "status": "Documentation", | ||
| "publisher": "Apple" | ||
| }, | ||
| "DASH": { | ||
| "href": "https://www.iso.org/standard/65274.html", | ||
| "id": "DASH", | ||
| "title": "Information technology — Dynamic adaptive streaming over HTTP (DASH) — Part 1: Media presentation description and segment formats", | ||
| "status": "Standard", | ||
| "publisher": "ISO" | ||
| } | ||
| } | ||
| </pre> | ||
|
|
||
| <pre class="anchors"> | ||
| url: https://www.iso.org/standard/65274.html#; spec: DASH; type: dfn; | ||
| text: emsg | ||
| text: scheme_id_uri | ||
| text: value | ||
| text: message_data | ||
| text: timescale | ||
| text: event_duration | ||
| text: presentation_time_delta | ||
| text: presentation_time | ||
| text: id | ||
| text: DASHEventMessageBox | ||
| text: emsg | ||
| text: scheme_id_uri | ||
| text: value | ||
| text: message_data | ||
| text: timescale | ||
| text: event_duration | ||
| text: presentation_time_delta | ||
| text: presentation_time | ||
| text: id | ||
| </pre> | ||
|
|
||
| # Introduction # {#introduction} | ||
|
|
@@ -99,42 +101,42 @@ For convenience, the follow box definition is reproduced from [[DASH]], section | |
| ```cpp | ||
| aligned(8) class DASHEventMessageBox extends FullBox('emsg', version, flags = 0) | ||
| { | ||
| if (version==0) { | ||
| string scheme_id_uri; | ||
| string value; | ||
| unsigned int(32) timescale; | ||
| unsigned int(32) presentation_time_delta; | ||
| unsigned int(32) event_duration; | ||
| unsigned int(32) id; | ||
| } else if (version==1) { | ||
| unsigned int(32) timescale; | ||
| unsigned int(64) presentation_time; | ||
| unsigned int(32) event_duration; | ||
| unsigned int(32) id; | ||
| string scheme_id_uri; | ||
| string value; | ||
| } | ||
| unsigned int(8) message_data[]; | ||
| if (version==0) { | ||
| string scheme_id_uri; | ||
| string value; | ||
| unsigned int(32) timescale; | ||
| unsigned int(32) presentation_time_delta; | ||
| unsigned int(32) event_duration; | ||
| unsigned int(32) id; | ||
| } else if (version==1) { | ||
| unsigned int(32) timescale; | ||
| unsigned int(64) presentation_time; | ||
| unsigned int(32) event_duration; | ||
| unsigned int(32) id; | ||
| string scheme_id_uri; | ||
| string value; | ||
| } | ||
| unsigned int(8) message_data[]; | ||
| } | ||
| ``` | ||
|
|
||
| ### Semantics ### {#emsg-semantics} | ||
|
|
||
| <a>scheme_id_uri</a> MUST be set to <dfn><code>https://aomedia.org/emsg/ID3</code></dfn> to identify ID3v2 metadata [[ID3]]. | ||
| <dfn>scheme_id_uri</dfn> SHALL be set to <dfn export><code>https://aomedia.org/emsg/ID3</code></dfn> to identify ID3v2 metadata [[ID3]]. | ||
|
|
||
| <a>value</a> may either be an absolute or relative user-specified URI which defines the semantics of the id field. | ||
| <dfn>value</dfn> may either be an absolute or relative user-specified URI which defines the semantics of the id field. | ||
| Any relative URI is considered to be relative to the <a>scheme_id_uri</a>. | ||
|
|
||
| <a>message_data</a> MUST contain complete ID3 version 2.4 data [[ID3]]. | ||
| <dfn>message_data</dfn> SHALL contain complete ID3 version 2.4 data [[ID3]]. | ||
|
|
||
| In general, ID3 don't carry a duration and in those cases the <a>event_duration</a> field should be set to <code>0xFFFFFFFF</code>. | ||
| If in a particular case, the ID3 message carries a duration, it should be reflected in the <a>event_duration</a> field. | ||
|
|
||
| The <a>presentation_time</a> must be within the time interval of the fragment. | ||
| The <dfn>presentation_time</dfn> must be within the time interval of the fragment. | ||
|
|
||
| The <a>id</a> field is not restricted in this version of the specification. | ||
| The <dfn>id</dfn> field is not restricted in this version of the specification. | ||
|
|
||
| ## Signaling ## {#meta-signaling} | ||
|
|
||
| Files compliant to this specification should signal it using the brand <code><dfn>aid3</dfn></code> as part of the list compatible brands in the file type box. | ||
| Manifest formats using files compliant to this specification may signal these files using the following URN: <dfn><code>urn:aomedia:cmaf:id3</code></dfn>. | ||
| Files compliant to this specification should signal it using the brand <dfn export><code>aid3</code></dfn> as part of the list compatible brands in the file type box. | ||
| Manifest formats using files compliant to this specification may signal these files using the following URN: <dfn export><code>urn:aomedia:cmaf:id3</code></dfn>. | ||