[vlc-devel] How to force audio codec format to VLC_CODEC_F32L?

Peter Tap ptrtap at yahoo.com
Thu Mar 12 21:32:49 CET 2015

Can someone please help? I would appreciate any information that you can provide or point me to what I must debug.

     On Thursday, March 12, 2015 1:01 AM, Peter Tap <ptrtap at yahoo.com> wrote:



I have been trying to chase down a problem with audio distortion with VLC 2.1.5 code base. It happens only when the volume gain is changed from its default value of 100%.

The problem machine is an Ubuto 14.04 box with Openbox (no Unity). The audio driver is pure ALSA. There is no pulse audio. Audio output is six channels through a Soundblaster compatible card.

After going through VLC logs, I finally figured out that libsamplerate was being ignored although it was found. Today, I added some msg_Dbg statements in OpenRampler method of audio_filter/resampler/src.c and here is what I discovered:

Method OpenRampler first checks if the audio format is VLC_CODEC_FL32L. If not, it simply returns a generic error code.

On the machine where I have the problem, the audio format is reported as VLC_CODEC_S32L.

On another machine where I don't see the problem, the audio format is reported as VLC_CODEC_F32L for the same input file.

I am wondering if you can guide me in understanding where this problem is. It doesn't seem to be ALSA configuration issue as all the six speakers work as expected when the volume is set to 100%.

Thank you in advance for your help.


PS: I haven't had this problem with previous versions of VLC.

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