I was using Ubuntu 13.10 previously, and everything was working fine. Prior to upgrading to 14.04, I deleted some of the old kernels. Then, once I upgraded, the sound for .MKV was gone. I use VLC, but Totem could not play sound either. Other video files worked fined though.
I thought the issue was with codecs, so I installed all
libav*, gstreamer*, ubuntu-restricted-extras packages. Still nothing. Then I deleted the rest of the old kernels but it still didn't work.
I found a solution, which is using GNOME Mplayer, but this player is terrible - when transitioning scenes, you could see the lines in the video and, on larger files (4gb+) the sound breaks once in a while.
I would really like to be able to play it in VLC. I was thinking the issue was with VLC, since they don't have an "official" version for 14.04, but since it doesn't work on Totem as well, I don't think that's the issue.
I don't think the problem is with codecs, since I installed it, but is it possible that the codecs need some old kernels to work? How could I find out which version I need and download an older version of kernel?
avconv -i problem.mkv:
avconv version 9.13-6:9.13-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers built on May 9 2014 13:34:03 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1) Input #0, matroska,webm, from 'problem.mkv': Duration: 00:42:20.22, start: 0.000000, bitrate: N/A Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x720, PAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default) Stream #0.1: Audio: ac3, 48000 Hz, 5.1, fltp, 384 kb/s (default) At least one output file must be specified