Allow mp3 audio codec for mpeg2ts containers in MSE

media/test/data/README

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 bear-320x240.webm - WebM encode of bear.1280x720.mp4 resized to 320x240.
 bear-320x240-video-only.webm - The video track of bear-320x240.webm.
 bear-320x240-audio-only.webm - The audio track of bear-320x240.webm.
 bear-vp9.webm - VP9 video only WebM file.
 bear-vp9-opus.webm - VP9 Video with Opus Audio.
 bear-vp8-webvtt.webm - WebM VP8 video with WebVTT subtitle track.
@@ skipping 242 matching lines @@
 
 media/test/data/bear-eac3-only-frag.mp4
   EAC3 audio in framented MP4, generated with
   ffmpeg -i bear.eac3 -acodec copy -movflags frag_keyframe bear-eac3-only-frag.mp4
 
 // Mpeg2ts stream with AAC HE audio that uses SBR
 media/test/data/bear-1280x720-aac_he.ts
   Generated by the following command:
   ffmpeg -i bear-1280x720.mp4 -c:v libx264 -c:a libfdk_aac -profile:a aac_he  bear-1280x720-aac_he.ts
 
+// Mpeg2ts streams MP3 audio
+media/test/data/bear-audio-mp4a.6B.ts
+  Generated by the following commands:
+    ffmpeg -i bear_pcm.wav -c:a mp3 -ar 44100 bear-audio-mp4a.6B.ts
+media/test/data/bear-audio-mp4a.69.ts
+  Generated by the following commands:
+    ffmpeg -i bear_pcm.wav -c:a mp3 -ar 22050 bear-audio-mp4a.69.ts
+
 // MP4 file with HEVC
 media/test/data/bear-320x240-v_frag-hevc.mp4
   HEVC video stream in fragmented MP4 container, generated with
   ffmpeg -i bear-320x240.webm -c:v libx265 -an -movflags faststart+frag_keyframe bear-320x240-v_frag-hevc.mp4
 
 // Multi-track MP4 file
 // (c) copyright 2008, Blender Foundation / www.bigbuckbunny.org
 media/test/data/bbb-320x240-2video-2audio.mp4
   Generated using following commands
   // Download the source file with 1 video and 1 audio stream.
   wget http://distribution.bbb3d.renderfarming.net/video/mp4/bbb_sunflower_1080p_30fps_normal.mp4
   // Generate a scaled down to 320x240 video + 2 channel AAC LC audio from the source file.
   ffmpeg -i bbb_sunflower_1080p_30fps_normal.mp4 -c:v libx264 -crf 36 -vf  scale=320:240 -c:a libfdk_aac -ac 2 -t 24 bbb1.mp4
   // Generate a file with the original video scaled down to 320x240 and flipped upside down and sine wave instead of audio.
   ffmpeg -i bbb_sunflower_1080p_30fps_normal.mp4 -f lavfi -i "sine=frequency=500:sample_rate=48000" -map 0:v -map 1:a -c:v libx264 -crf 36 -vf scale=320:240,vflip -c:a libfdk_aac -ac 2 -t 24 bbb2.mp4
   // Combine the two files generated above into a single fragmented .mp4 file with 2 video and 2 audio tracks.
   ffmpeg -i bbb1.mp4 -i bbb2.mp4 -map 0:0 -map 0:1 -map 1:0 -map 1:1 -c:v copy -c:a copy -movflags frag_keyframe+omit_tfhd_offset+separate_moof bbb-320x240-2video-2audio.mp4
 
 // Multi-track WebM file
 media/test/data/multitrack-3video-2audio.webm
     //Generated using following commands:
     ffmpeg -f lavfi -i color=c=red:size=320x240 -t 5 -c:v libvpx red.webm
     ffmpeg -f lavfi -i color=c=green:size=320x240 -t 5 -c:v libvpx green.webm
     ffmpeg -f lavfi -i color=c=blue:size=160x120 -t 10 -c:v libvpx blue.webm
     ffmpeg -f lavfi -i "sine=frequency=300:sample_rate=48000" -t 10 -c:v libvpx a300hz.webm
     ffmpeg -f lavfi -i "sine=frequency=500:sample_rate=48000" -t 5 -c:v libvpx a500hz.webm
     ffmpeg -i red.webm -i green.webm -i blue.webm -i a300hz.webm -i a500hz.webm -map 0 -map 1 -map 2 -map 3 -map 4  multitrack-3video-2audio.webm