[vlc-devel] Audio problem: latest git always tries S/PDIF?

[Juha Jeronen]

Hi all,

I noticed that when the audio output module is left as default, the
latest 1.2-git [3fb5c74cc2f6dd5bb1a7d80d9d650335b5d6cd8e] errors when
opening a DVD source. The log says that

---8<---8<---8<---

[0x876d3c4] alsa audio output error: cannot open ALSA device
`iec958:AES0=0x2,AES1=0x82,AES2=0x0,AES3=0x2' (Error message unavailable
(use strerror_r instead of
strerror)!)                                                                                                                 

[0x876d3c4] jack audio output error: failed to connect to JACK server

---8<---8<---8<---

This machine doesn't have S/PDIF (iec958). I checked the VLC
preferences, but "Use S/PDIF when available" is not enabled. Earlier
versions didn't try S/PDIF when not instructed to :)

Aside from having to close the error dialog once per VLC session, there
are no other problems. The audio plays back correctly.

The environment is a Debian Squeeze + KDE4.x. JACK is not installed -
ALSA is the correct output module.

It looks like it's trying ALSA with S/PDIF > JACK > ALSA analog. The
first two fail (as expected), and the third succeeds. Then the GUI
detects the error and opens the error dialog... which isn't really
necessary, since the sound works.

If the ALSA device in the ALSA output module section of VLC preferences
is forced to the onboard sound chip explicitly, no error is generated,
but the sound becomes extremely loud and distorted. It sounds like
digital clipping - as if it's not limiting the volume to 100%. I have
set volume as 256 (out of 1024) in the VLC audio preferences, so it
should do the limiting. This may have something to do with the
audio-related commit Rémi mentioned the other day...

My ALSA is a bit old (1.0.21), but it's from a Debian default kernel. I
think they don't ship 1.0.24 yet.

So, is the error supposed to happen or is there a bug in S/PDIF handling?

 -J