[Feature Request] Add initial audio codec support

[KunXi-Fox]

Context

Currently rx-player use the first audio codec as default audio codec:

rx-player/src/core/stream/period/period_stream.ts

Lines 472 to 485 in 7b24c52

	function getFirstDeclaredMimeType(adaptation: IAdaptation): string {
	const representations = adaptation.representations.filter(
	(r) => r.isPlayable() !== false,
	);
	if (representations.length === 0) {
	const noRepErr = new MediaError(
	"NO_PLAYABLE_REPRESENTATION",
	"No Representation in the chosen " + adaptation.type + " Adaptation can be played",
	{ tracks: [toTaggedTrack(adaptation)] },
	);
	throw noRepErr;
	}
	return representations[0].getMimeTypeString();
	}

If I want to use another audio codec based on user preferences, I need to manually call setAudioTrack method. This is works at most of cases except the device that not support seamless audio codec switch, which means every audio codec changes will lead to a reload.

Solution

Provide a initialAudioCodec option and change getFirstDeclaredMimeType method to based on initialAudioCodec, if no initialAudioCodec specified, then fallback to first available audio codec.

[peaBerberian]

Hi @KunXi-Fox,

Normally you can set the audio track based on codecs before the RxPlayer has made any choice (and thus not have a reload) by reacting to the newAvailablePeriods event. For example:

player.addEventListener("newAvailablePeriods", (periods) => {
  for (const period of periods) {
    const audioTracks = player.getAvailableAudioTracks(period.id);
    
    // use external logic to select the wanted audio track based on the codec
    const chosenAudioTrack = chooseAudioTrack(audioTracks);

    if (chosenAudioTrack) {
      player.setAudioTrack({
        periodId: period.id,
        trackId: chosenAudioTrack.id,
      });
    }
  }
});

https://developers.canal-plus.com/rx-player/doc/api/Track_Selection/setAudioTrack.html#setting-the-audio-track-as-soon-as-possible
https://developers.canal-plus.com/rx-player/doc/api/Player_Events.html#newavailableperiods

At what point do you update the audio track? If it's e.g. at the "LOADED" state it may be late because the RxPlayer already has loaded audio data (from the previous track).

[KunXi-Fox]

Yeah, just as you said, I set the initial audio codec at LOADED state. I'll try set it when first newAvailablePeriods event fired and see if it solve the problem.

[KunXi-Fox]

Unfortunately, seems newAvailablePeriods not been fired for single period assets.

[KunXi-Fox]

availableAudioTracksChange seems works fine, Thanks.

[peaBerberian]

Unfortunately, seems newAvailablePeriods not been fired for single period assets.

I'm not sure if I understand the problem. newAvailablePeriods is the intended event for the initial track and quality selections and should be sent for all contents even those with a single Period (whereas availableAudioTracksChange indicate that the choice for the currently-played Period is available or has changed).

For availableAudioTracksChange the RxPlayer may have already chosen an audio track and loading it before starting that Period so it may be too late for an initial track choice.
That event is more about the menu you show to your user so he/she can select the track he/she wants from a list once it already began playing (as the user generally just cares/know about the Period that is currently playing, not about future or past ones).

You don't have a newAvailablePeriods event that is being triggered on your content?

[KunXi-Fox]

Hi @peaBerberian , with newAvailablePeriods I'm able to set initial audio data, unfortunately for some reason, sometimes I saw below error, then during period switch, I notice a infinite loading.

TS: Subject already added for audio and Period 30

Do you have any idea why this happens?

[peaBerberian]

OK you seem to be encountering an issue.

What is the code you're calling on newAvailablePeriods?

[KunXi-Fox]

something like ⬇ , one more thing is the issue seems only happen on lower end devices, e.g. LG2019, Hisense U4

function handleNewAvailablePeriods(periods) {
    for(const period of periods) {
        const allTracks = this.getAvailableAudioTracks(
            period.id
        );

        const changeToTrack = allTracks.find(track => track.representations[0]?.codec === this.currentCodec);

        if (changeToTrack) {
            this.setAudioTrack({
                periodId: period.id,
                trackId: changeToTrack.id.toString(),
                switchingMode: changeToTrack.active ? 'seamless' : 'reload',
            })
        }
    }
}

[peaBerberian]

Even if we shouldn't have a problem with that, you shouldn't have to call setAudioTrack if that audio track is already set to active.

Can you retry without that? I check in the meantime if I can see what happens.

[KunXi-Fox]

The issue still there even prevent call setAudioTrack when track is active. I add log for call track, hopefully it will provide some information.

The step I reproduce the issue is:

1. Play a multiple periods + multiple audio track asset
2. After at least one period switch, then switch to another audio track (use reload way)
3. During period switch, the issue will happens in most of cases.

rx-player.es5.js.zip

[peaBerberian]

OK thanks.

It could also be helpful to have the full debug logs for that scenario. Can you set:

RxPlayer.LogLevel = "DEBUG"
RxPlayer.LogFormat = "full"

Reproduce and communicate back logs?

[KunXi-Fox]

Hi @peaBerberian , below was the detail log:

1738983734378.log

[KunXi-Fox]

BTW, this PR did fix the infinite loading issue even when I saw the error on console.

• TracksStore keeps the last reference in case of several being communicatedr #1643