Add support for AVC fmp4 fragments found in Apple Advanced HEVC/H.264 stream

[robwalch]

This PR will...

Add support for AVC fmp4 fragments found in Apple Advanced HEVC/H.264 stream

Why is this Pull Request needed?

Playback of https://devstreaming-cdn.apple.com/videos/streaming/examples/bipbop_adv_example_hevc/master.m3u8 without JavaScript exceptions.

When playing this stream, mp4-tool functions such as getStartDTS, offsetStartDTS , and getDuration would throw exceptions when encountering track fragment boxes for unknown track types* not accounted for in the init data (initData[id] is undefined).

These changes ignore those track fragments so that we only deal with the audio and video fragments we're parsing time/duration for.

*Track types added to init data:

const type: HdlrType = { soun: ElementaryStreamTypes.AUDIO, vide: ElementaryStreamTypes.VIDEO }[hdlrType];
if (type) {

Are there any points in the code the reviewer needs to double check?

Replaced some array methods where appropriate (map > reduce or forEach).

This is also broken in v0.x, so a patch in master should be made for v0.15.

Demo:

https://deploy-preview-3274--hls-js-dev.netlify.app/demo/?src=https%3A%2F%2Fdevstreaming-cdn.apple.com%2Fvideos%2Fstreaming%2Fexamples%2Fbipbop_adv_example_hevc%2Fmaster.m3u8&demoConfig=eyJlbmFibGVTdHJlYW1pbmciOnRydWUsImF1dG9SZWNvdmVyRXJyb3IiOnRydWUsInN0b3BPblN0YWxsIjpmYWxzZSwiZHVtcGZNUDQiOmZhbHNlLCJsZXZlbENhcHBpbmciOi0xLCJsaW1pdE1ldHJpY3MiOi0xfQ==

Checklist

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• API or design changes are documented in API.md

[robwalch]

Hi @kanongil,

You were the last person to provide enhancements to fmp4 parsing. Would you mind reviewing these changes? They aren't final as the parsed fragment durations are incorrect. Any pointers would be much appreciated! Thank you.

[itsjamie]

The file here advertised with the major brand mp42, not the CMAF brand, and is multi-trun. So we have durations split across multiple track runs on the same track. I see below you've started to account for this, but it'll be more parsing issues like this. It may make sense in the future to pull apart the parser to make a brand-specific parser for CMAF since it is intended to be much simpler.

[itsjamie]

This warning is occurring for track-id 2 on the test content because we do not handle the clcp style of hdlr. It's a closed caption track.

hls.js/src/demux/mp4demuxer.js

Lines 273 to 287 in c19056b

	if (hdlr) {
	const hdlrType = MP4Demuxer.bin2str(hdlr.data.subarray(hdlr.start + 8, hdlr.start + 12));
	let type = { 'soun': 'audio', 'vide': 'video' }[hdlrType];
	if (type) {
	// extract codec info. TODO : parse codec details to be able to build MIME type
	let codecBox = MP4Demuxer.findBox(trak, ['mdia', 'minf', 'stbl', 'stsd']);
	if (codecBox.length) {
	codecBox = codecBox[0];
	let codecType = MP4Demuxer.bin2str(codecBox.data.subarray(codecBox.start + 12, codecBox.start + 16));
	logger.log(`MP4Demuxer:${type}:${codecType} found`);
	}
	result[trackId] = { timescale: timescale, type: type };
	result[type] = { timescale: timescale, id: trackId };
	}
	}

MP4Box.js output of track info for test content

[robwalch]

I got rid of that. Now fragment boxes for those tracks are ignored. Thanks so much for pointing this out!