Simplify/allow selection of multiple renderers of the same type in DefaultTrackSelector.

I want play multi sound in same time(simultaneously) in exoplayer but it only play mediaSource1 and mediaSource2. I want play all mediaSources at the same time(simultaneously)

My code with exoplayer is:

>
Uri uri1 = Uri.parse(videopath);
Uri uri2 = Uri.parse(audio_a.getAbsolutePath());
Uri uri3 = Uri.parse(audio_b.getAbsolutePath());
Uri uri4 = Uri.parse(audio_c.getAbsolutePath());

MediaSource mediaSource1 = buildMediaSource(uri1);
MediaSource mediaSource2 = buildMediaSource(uri2);
MediaSource mediaSource3 = buildMediaSource(uri3);
MediaSource mediaSource4 = buildMediaSource(uri4);

MergingMediaSource mediaSource = new MergingMediaSource(mediaSource1, mediaSource2, mediaSource3, mediaSource4);

exoPlayer.prepare(mediaSource, false, false);

>

please help me
thanks