gnittor@xxxxxxxxxxx wrote:
> hello,
> What is the best way to use this card, for single application at a time operation, without resampling? I am interested in best quality as I want to only use this card for music. software mixing is not important (i plan to use another soundcard as the default). Sampling rate should depend on the audio source.
>
> MAudio Revolution 7.1
> linux 2.6.23-rt1 #1 PREEMPT RT
> alsa 1.0.14
> debian unstable
>
> what i've done so far:
>
> - using it as default seems to work ok in every app (sw mixing ok) but plays at 48khz, while 44.1khz audio sounds slower than original
> cat /proc/asound/card0/pcm0p/sub0/hw_params
> access: MMAP_INTERLEAVED
> format: S32_LE
> subformat: STD
> channels: 2
> rate: 48000 (48000/1)
> period_size: 1024
> buffer_size: 16384
> tick_time: 1000
>
>
> - using hw:0,0 does not seem to work in any application. i get device busy. (also for hw:0,1 and hw:0,2)
>
>
> - using plughw:Revolution71 in audacious works fine, but the value of period_size looks odd
> cat /proc/asound/card0/pcm0p/sub0/hw_params
> access: MMAP_INTERLEAVED
> format: S32_LE
> subformat: STD
> channels: 2
> rate: 44100 (44100/1)
> period_size: 4412
> buffer_size: 22052
> tick_time: 1000
>
>
> - using plughw:Revolution71 in xine produces crackles (stops every 1-2 sec for a little)
> cat /proc/asound/card0/pcm0p/sub0/hw_params
> access: MMAP_INTERLEAVED
> format: S32_LE
> subformat: STD
> channels: 2
> rate: 44100 (44100/1)
> period_size: 4096
> buffer_size: 32768
> tick_time: 1000
>
>
> - using xine & jack (at 44100) produces crackles (no matter what settings for frames/period & periods/buffer i've tried)
> cat /proc/asound/card0/pcm0p/sub0/hw_params
> access: MMAP_INTERLEAVED
> format: S32_LE
> subformat: STD
> channels: 8
> rate: 44100 (44100/1)
> period_size: 16
> buffer_size: 96
> tick_time: 1000
>
>
> - using xine & jack (at 48khz) no crackles but sounds slow (using either audacious or xine)
> cat /proc/asound/card0/pcm0p/sub0/hw_params
> access: MMAP_INTERLEAVED
> format: S32_LE
> subformat: STD
> channels: 8
> rate: 44100 (44100/1)
> period_size: 16
> buffer_size: 96
> tick_time: 1000
>
>
>
> The problem is with 44.1 audio and xine. It seems that it is played without crackles only with the card in 48khz but sounds slower.
>
>
> I have tried setting period_size and buffer_size in asoundrc (as this is the only difference I could find between xine and audacious playng using plughw:Revolution71) but with no success.
> Also the only way I could get a virtual device to work in asoundrc was using plughw as such:
>
> pcm.rev {
> type plug
> slave {
> pcm "plughw:Revolution71"
> format S32_LE
> }
> }
>
>
> Any help appreciated
>
I have a Revolution 5.1 which uses the same driver. Alsa supports all
frame rates that the hardware does and the sound is awesome. I use it
to generate binaural beats through an app I wrote. You can get it at
http://sourceforge.net/projects/discord/ if you want; it allows setting
frame rate.
I recommend that you go to planet ccrma
http://ccrma.stanford.edu/planetccrma/software/ if you are interested in
quality sound. They have a site with enhancements to stock linux to
support sound.
Avoid sound servers as they do internal conversion of frame rate. You
want to play your music at a hardware frame rate that the card
supports. The rev 5.1 supports 44.1, 48, 64, 88.2, 96, 176.4 and 196
(from memory). The program I wrote will use the closest hardware rate
if you ask for a non supported rate. It prints out the rate being
used. Alsa has all kinds of neat features if you use it directly
instead of through a dumbed down interface.
Don't use default at rates other than 48 as it will convert everything
to that rate, the only rate it supports. Great for casual support, not
so great for wonderful sound.
The application you use and how it interfaces to alsa is important.
I've had good luck with mplayer and xmms using direct alsa plugin.
Good luck.
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