Enhanced silence skipping implementation

[jakoss]

Issue description

We are playing HLS tracks and facing skip silence issues. Attached project reproduces problem exactly. On some track, especially on film music, skip silence just rolls over few second with no apparent reason. This produces very strange audio glitches and it's confusing for the end user.

Reproduction steps

SkipSilenceRepro.zip
Run attached project, then seek to 40th second. The issue is very apparent on span 40-46 seconds of this track. If we turn off skip silence - everything works perfectly.

Link to test content

Test content is embedded in attached reproduction code

A full bug report captured from the device

These is no bug on the device, no strange logs or errors in console.

Version of ExoPlayer being used

2.11.4

Device(s) and version(s) of Android being used

Any device we tested it on - Emulators, Samsung S6, OnePlus 7, Samsung Note 10 and so on

[andrewlewis]

The implementation in ExoPlayer at the moment is quite simple and doesn't fade the audio out/in across silent portions. I guess this may be causing the strange artifacts when there is music in the stream. We tested this feature on spoken content without music. We have a task on our roadmap to improve silence skipping (including ramping audio out/in) but it is currently low priority.

In the short term you may want to try tweaking the constants used by SilenceSkippingAudioProcessor. See the commits on #6705, which added the APIs to allow this. If you can get all the music to be classified as non-silence that may remove the artifacts.

@Samrobbo Could you take a look at this at some point?

[jakoss]

Thanks for the answer, i will try and tweak those constants