Hi,
I'm running slackware-current on my main desktop, which uses Alsa directly for
sound, there is
no sound server like PulseAudio or Jack.
I use VLC as a principal multimedia player and until about 2 months ago,
everything worked
fine : Slackware was running alsa 1.0.26 and I could use whatever version of
VLC, even git,
with no issue.
In may, Slackware-current upgraded to 1.0.27 alsa and then upgraded to the
bugfix .1 then .2
releases.
Since then, any newer version of VLC that I try (self compiled from git)
exhibit the same wrong
behaviour : every time I watch a film with 5.1 surround sound, only two
channels are played,
and I often miss the voices, for instance.
I raised the issue on the VLC forum and they pointed me to the following logs
in the VLC
output :
Hardware PCM card 0 'HDA ATI SB' device 0 subdevice 0Its setup is: stream
: PLAYBACK access
: MMAP_INTERLEAVED format : S32_LE subformat : STD channels
: 2 rate : 48000 exact rate
: 48000 (48000/1)
followed by :
Hardware PCM card 0 'HDA ATI SB' device 0 subdevice 0Its setup is: stream
: PLAYBACK access
: MMAP_INTERLEAVED format : S32_LE subformat : STD channels
: 2 rate : 48000 exact rate
: 48000 (48000/1)
The previous output from working VLC showed a downmixing line :
BUFFER_BYTES: [1024 655360000]TICK_TIME: ALL[0x7ffb0c002358] freetype spu text
debug:
using fontsize: 2[0x7ffb0c002358] main spu text debug: using text renderer
module
"freetype"[0x855778] alsa audio output debug: downmixing from 6 to 2
channels[0x855778] alsa audio output debug: final HW setup:
According to the VLC developers, channel mapping support, introduced by alsa
1.0.27, was
added to VLC in december 2012, and this must have been kicking in since
Slackware added
alsa 1.0.27.
Their analysis is that, although the hardware seem only to support two
channels, the softvol
plugin is reporting 5.1 support and advertising it. Thus VLC automatically
choose the 5.1
output and do not downmix it.
However, although the chip (Realtek ALC889A) indeed support 5.1 sound, and
although I
indeed have several audio port on my mainboard, I only plugged stereo speakers
and thus
got a problem.
I tried setting up force downmix in /etc/asound.conf like this :
pcm.!surround51 {
type vdownmix
slave.pcm "default"
}
pcm.!surround40 {
type vdownmix
slave.pcm "default"
}
But to no avail.
Is this a bug I should report or is there a proper configuration that must be
used?
I can provide a alsa-info output if necessary.
Best regards,
Richard Van Den Boom
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