Re: hdsp vs 16bit vs dmix

[Takashi Iwai <tiwai@suse.de>]

At Fri, 09 Jan 2004 00:49:34 +0900,
Patrick Shirkey wrote:
> 
> Takashi Iwai wrote:
> > At Thu, 08 Jan 2004 02:29:13 +0900,
> > Patrick Shirkey wrote:
> > 
> >>I am seeing strange things happen while using the hdsp and dmix plugin 
> >>and aplay as a test app.
> >>
> >>JACK works perfectly.
> >>
> >>I can get sound from aplay if I use this commandline:
> >>
> >>aplay -f cd -D plughw audio.wav
> >>Playing WAVE 'audio.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, 
> >>Stereo
> >>underrun!!! (at least 40.147 ms long)
> >>underrun!!! (at least 86.223 ms long)
> >>underrun!!! (at least 145.116 ms long)
> >>underrun!!! (at least 79.109 ms long)
> >>underrun!!! (at least 248.555 ms long)
> >>underrun!!! (at least 180.442 ms long)
> >>underrun!!! (at least 96.117 ms long)
> >>Aborted by signal Interrupt...	
> >>
> >>But I get an xrun every second or so which makes the card useless for 
> >>native alsa apps .
> > 
> > 
> > i'm not sure which plugin plays wrong yet.
> > 
> > run aplay with -v option and see which plugins and what configurations
> > are used.  for example, if the native hardware requires 32bit samples,
> > prepare 32bit samples WAV instead of 16bit, and reduce the plugin.
> > i don't think the rate conversion is used, so the plugins are linear,
> > route, and copy plugins.
> > 
> > my rough guess is the copy plugin.  try aplay -M option, so that mmap
> > mode is used.
> > 
> 
> IMO the test case should be a 16bit file because this is the CD standard.

i asked it only for catching the bug.  of course, 16bit 2ch WAV should
be supported.

> -------
>   aplay -v -M -f cd -D plughw audio.wav
> Playing WAVE 'audio.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, 
> Stereo
> Plug PCM: Route conversion PCM (sformat=S32_LE)
> Transformation table:
(snip)

ok, it's not in copy plugin.

> Slave: Hardware PCM card 0 'Hammerfall DSP' device 0 subdevice 0
> 
> Its setup is:
> stream       : PLAYBACK
> access       : MMAP_NONINTERLEAVED
> format       : S32_LE
> subformat    : STD
> channels     : 18
> rate         : 44100
> exact rate   : 44100 (44100/1)
> msbits       : 24
> buffer_size  : 8192
> period_size  : 4096
> period_time  : 92879

the buffer isn't large, it's 180 msec.
to get rid of the possibility of general kernel scheduling problem,
try to start aplay with nice -10 (as root)

	# nice -n -10 aplay foo.wav

> >>  aplay -f cd -D default audio.wav
> >>ALSA lib pcm.c:1900:(snd_pcm_open_conf) Cannot open shared library 
> >>/usr/lib/alsa-lib/libasound_module_pcm_plughw.so
> >>aplay: main:502: audio open error: No such file or directory
> > 
> > 
> > this one is clear.  there is no plughw type.
> > it's a defined pcm name.
> > 
> 
> Hmm. This would appear to be a problem. While I'm not ecouraging people 
> to use the hdsp as a standard consumer playback device... My customer 
> (who runs windows mostly) is expecting to be able to view videos etc 
> with this device simply because he can in his windows env. Should I be 
> encouraging him to purchase a second card or can this be fixed using ALSA?

sorry, i can't measure how deep the problem is.  i have no this card
by myself.  but viewing a video with hdsp is like going shoping with
Ferrari, i'd like to say :)


Takashi


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