Add support for emsg ID3 metadata in fmp4 segments #4458
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robwalch
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Adding reference link for data structure for reference/posterity (link in the original issue is incorrect or out of date): |
| } from '../utils/mp4-tools'; | ||
| import { dummyTrack } from './dummy-demuxed-track'; | ||
| import type { HlsEventEmitter } from '../events'; | ||
| import type { HlsConfig } from '../config'; | ||
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| const emsgSchemePattern = /\/emsg[-/]ID3/i; |
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not sure about best practices here, but are we using this looser match to handle both "https://aomedia.org/emsg/ID3" (defined in: https://aomediacodec.github.io/av1-id3/) and the outdated "https://developer.apple.com/streaming/emsg-id3"? If so, should we be more explicit with those two matches for potential future-proofing concerns?
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For the purposes of this contribution, I wanted the broadest support for available test content, but could not explicitly add support for undocumented schemes. Perhaps other players are even less strict that this?
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| timeScale = readUint32(data, 12); | ||
| presentationTimeDelta = readUint32(data, 16); | ||
| eventDuration = readUint32(data, 20); |
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Looks like this is unused in our codebase, but should we make eventDuration = undefined or NaN or some other special value in cases where its value is 0xFFFFFFFF for clarity? From the spec:
In general, ID3 don’t carry a duration and in those cases the event_duration field should be set to 0xFFFFFFFF. If in a particular case, the ID3 message carries a duration, it should be reflected in the event_duration field.
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Since it is part of the spec, it is included for future use. It would help to have sample content with event durations defined. For everything else we have an open issue with some discussion on the subject #3879 (duration=Infinity until next cue).
| id3Track, | ||
| timeOffset, | ||
| id3InitPts, | ||
| id3InitPts |
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not having enough context here, wondering why we're using pts as dts here? Worried we might get some cross-browser inconsistencies with timings if we're not careful.
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The use of both PTS and DTS here is legacy code for dealing with MPEG-TS 33-bit timestamp rollover (this is not new code, just code I moved into flushTextTrackMetadataCueSamples). Since we can expect all emsg samples to have identical pts and dts, we can use the same value for both inputs.
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Hi, We really want to use this feature, but from what I see it's not on the latest tag (v1.1.5), is there any ETA for the next release? Thanks! Eran |
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Hello there, great feature, is there any ETA for the next release? Thanks |
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Hi @erankor and @petronioamaral, This feature is in the latest beta release: v1.2.0-beta.1. If you have time next week, please try it out next week and provide feedback. v1.2.0 will be released soon. |
Hi @robwalch I tested here and seems work very well, let us know when will be merge with the v1.2.0. |
This PR will...
Add support for emsg timed metadata within fragmented MP4.
These changes allow for timed metadata delivery (ID3 via emsg) for use cases such as content labeling and advertising in CMAF streams in the same way HLS.js currently supports ID3 in other container formats.
HTMLMediaElementtext track and cues generated by HLS.js are similar in timing and content to those added with native HLS playback in Safari.Supported schemas include any url containing "/emsg/ID3" or "/emsg-id3" (case insensitive).
Sample test streams from #2360:
Resolves issues:
Closes #2360
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