mp4 with an AAC-LC track: No audio. Tested with 2.1.2.

[b3tron]

Hi Everyone,

I have been testing VLC 2.1.2 playing a mp4 that has an AAC-LC audio track. The mp4 video playback is fine as we'd expect. However, I do not get any audio on VLC 2.1.2 on any OS. From this page I can see that VLC supports AAC. I was assuming that AAC-LC is would also be supported. This does not seem to be the case.

Can anyone comment on VLC's playback of mp4's with an AAC-LC audio track? Maybe I just need to reconfigure something to get the audio to work properly?

Here is a sample for everyone to play with (you might need to right click and save this as, then open the file in VLC).

Thanks in advance. I'm happy to provide any additional information.

[Jean-Baptiste Kempf]

You should probably file a bugreport.

[Lotesdelere]

This stream is quite strange, especially the audio:

Code: Select all

Audio Format : AAC Format profile : LC Bit rate mode : Constant Bit rate : 1 322 Kbps Nominal bit rate : 132 Kbps Channel(s) : 2 channels Channel positions : Front: L R Sampling rate : 48.0 KHz

I wonder where these 1 322 kbps come from...

MP4Box fails at extracting the streams, so does L-Smash.
But FFplay is playing it, whilst many other splitters fail.
So remuxing the file with FFmpeg makes a working file:

Code: Select all

ffmpeg -i NO_AUDIO_VLC.mp4 -vcodec copy -acodec copy New.mp4

I'm just curious to know which tool has made the original file.
Don't use it anymore...

[b3tron]

Thanks for the fast replies, guys.

I've opened a ticket in TRAC:

I found a secondary issue with this file when opened via the "Open Network..." option.

Steps to replicate:
1) Open VLC > Open Network...
2) Punch in this URL:"https://dl.dropboxusercontent.com/u/634 ... O_VLC.mp4/" (w/o quotes)
VLC displays one or two frames then the video window closes. This behavior does not happen locally. When the asset is played locally the video plays like we expect. However, we don't get audio as discussed above.

Both issues are in the TRAC ticket.

Thanks again everyone!!!

[Jean-Baptiste Kempf]

Sample added.

[b3tron]

Hi All,

A few months ago Bug #10520 was closed on Trac and this description was added:

Changed 5 months ago by fcartegnie

Component changed from Audio: misc. plugins to Demuxers

afaiu, this file uses "Interlaced" mdat ( moof,traf[n],mdat ). Our own demuxer expects moof,traf,mdat. So samples of track > 0 would be never read.

But here, it is an avformat demuxer problem, as our own demuxer gives up on fragmented mp4. Probably same issue dealing with interlaced samples.

However, I tested both issues noted in this thread with VLC 2.1.5 and both issues still exists. Can I get an update if these bugs will be resolved in a later release? The quote above does not mean a lot to me as I do not know the granular nature of how VLC decodes audio. Can someone explain/reword what the developer stated so I can understand? Another question is what's going on with interlaced samples and VLC?

I had assumed if a bug was closed it would have been resolved.

Thanks again everyone!

[b3tron]

I'm posting here for anyone who looks. Both of the issues noted above have been resolved in a VLC 3.0 nightly build from 9/23/14. Thanks everyone!!!