Audio issues with mp4 video playback

Issues related to applications and software problems

Audio issues with mp4 video playback

Postby taylorkh » 2012/07/10 14:19:44

I have VLC v1.1.13 player installed on CentOS 6.2 64 bit and for the most part it seems to be working fine. However, some but not all .mp4 video files exhibit one of two issues. No sound or broken up sound. I have some .mp4 files which play just fine. I believe all of them were downloaded from youtube for whatever difference that makes(?) Totem media player will not play .mp4 at all. In fact, after installing VLC I removed Totem as I have always used VLC.

I just built a CentOS virtual machine and tried playing one of the offending videos. Totem would not play it and wanted to install some codecs. I allowed it to do so and it downloaded half the Internet. After all this it says "Could not decode stream". I installed VLC and it will play the video but with no sound.

The offending .mp4 videos play fine in VLC 1.1.11 on Windows XP.

Obviously I am missing some required component. Just as obviously I have no clue as to what I need nor where to look. Past experience with VLC has shown that it generally installs everything it needs to play just about anything known to man.

I have looked at the CentOS wiki on setting up multimedia on CentOS 5. I believe my experiment on the virtual machine installed most of the packages shown there. I will track them down one by one and report back if that provides any information.

Any suggestions?

TIA,

Ken
taylorkh
 
Posts: 255
Joined: 2010/11/24 15:08:33
Location: North Carolina, USA

Re: Audio issues with mp4 video playback

Postby taylorkh » 2012/07/10 16:31:05

I am adding this as a reply as I cannot edit my original post(?)

A little more information... Looking at Tools; Codec Information in VLC I find the following differences:

mp4 file which plays sound

Stream 1
Type: Audio
Codec: MPEG AAC Audio (mp4a)
Channels: Stereo
Sample Rate: 44100 Hz

mp4 file which plays NO sound

Stream 1
Type: Audio
Codec: MPEG AAC Audio (mp4a)
Channels: 2
Sample Rate: 48000 Hz
Bits per sample: 16
Bitrate: 1536 kb/s

The data are the same on the Win XP VLC player where both files play sound. I am currently building an Ubuntu 12.04 virtual machine to see if the files play there. They played on Ubuntu 10.04 although I cannot boot the PC back to that OS without swapping hard drives so that my be a closer to last resort.

Ken
taylorkh
 
Posts: 255
Joined: 2010/11/24 15:08:33
Location: North Carolina, USA

Re: Audio issues with mp4 video playback

Postby taylorkh » 2012/07/10 22:00:57

And it keeps getting better NOT!

Ubuntu 12.04 64 bit repos contain VLC 2.01. And it plays the offending mp4 just fine, sound and all.

A fellow over at the Scientific Linux forum seemed to offer a possible solution by compiling VLC 2.0.2 for our flavor of Linux. I added his repo to my virtual machine and upgraded VLC 2.0.2 over top of 1.1.13 from RPMForge. It seems to work but still the offending file has no sound.

Interestingly when I try the play the offending mp4 with Totem I get a message that it needs plugins for:

- H.264.decoder
- MPEG-4 AAC decoder

neither of which it can find. Both of these seem to be present in VLC as I described earlier.

Ken
taylorkh
 
Posts: 255
Joined: 2010/11/24 15:08:33
Location: North Carolina, USA


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