'Twas brillig, and Lennart Poettering at 07/08/09 23:13 did gyre and gimble:
On Fri, 24.07.09 17:07, Colin Guthrie ([email protected]) wrote:
Hi Lennart,
From IRC, but as you're busy and I suspect this wont get immediate
attention, I'll post the details here for later :)
<coling> mezcalero, found a reliable way to produce some nasty
distortion that should not happen....
<coling> 1) >>> load-module module-remap-sink sink_name=mono
master=<alsa sink name> channels=1 master_channel_map=front-left
channel_map=mono
<coling> 2) >>> load-module module-remap-sink sink_name=fakestereo
master=mono channels=2 master_channel_map=mono,mono
channel_map=front-left,front-right
<coling> 3) PULSE_SINK=fakestereo paplay foo.wav
<coling> That's it.
<coling> Pretty nasty :s
<coling> mezcalero, incidentally, the above process also causes an
assert half the time too.
<coling> E: sink.c: Assertion '!s->thread_info.rewind_requested' failed
at pulsecore/sink.c:843, function pa_sink_render(). Aborting.
This fix should be fixed now in r7d49163. Please verify.
Seems to be OK now, thanks. :)
The distortion is probably caused because the handling of having two
mono channels is not what you expect. i.e. we probably just add them,
effectively amplifiyng the original signal 2x, which might easily
trigger clipping.
If you run PA in debug mode the resamplers/remixers will dump a little
table that tells you how each input channel is added up for the output
channels. Could you please find out that table and check out if that
triggers your problem? (i.e. both input mono channels are multiplied
by factor 1.0 instead of 0.5?)
Lennart
Here's the full output.
http://pastebin.com/me868948
From what I can see, yes when the second sink is loaded there is a
factor of 1.0 involved.
I presume there is no way to do what I originally wanted? (Incidentally
I don't specifically want this... it was more an experiment for a user
on the list who wanted to mix everything to the left channel but still
have a balance control - he was deaf in one ear).
Col
--
Colin Guthrie
gmane(at)colin.guthr.ie
http://colin.guthr.ie/
Day Job:
Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
Mandriva Linux Contributor [http://www.mandriva.com/]
PulseAudio Hacker [http://www.pulseaudio.org/]
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