On Mo, Aug 31 2009, Takashi Iwai wrote:
At Sun, 23 Aug 2009 09:55:18 +0000 (UTC), Halim Sahin wrote:
Hello, Is there a way to reduce latency on audiocard if the dmix plugin is in use? I am asking because there is a strange problem with asistive technologies which are outputing through alsa. E. G. speech-dispatcher takes almost a half sec to stop the speech-synthesizer. If the user navigates quickly through menus, there are simultane outputs at a time. (tested with an usb logitech headset, snd-intel8x0 based card, snd-hda-intel). The same problem can be reproduced by running mplayer with alsa output driver and pressing quickly left/right arrow. You should hear several samples at a time.
Using an sblive card which doesn't use dmix doesn't have such problems.
Using the dmix plugin should audio much faster to avoid this problem.
It's a bit hard to guess. This could be the difference of PCM drain implementation between hw and dmix, but a half second is still too long.
Could you prepare a small test case to reproduce the buggy behavior?
Yes that's easy: The following should be tested with active dmix. 1. login to a textconsole 2. mplayer -ao alsa your_favourite_file 3. Press space during playback.
Result: it takes about an half sec to stop the playback.
The second test would be: 1. login to a console 2. mplayer -ao alsa:device=hw=0,0 your_file 3. press space during playback Result: The playback stops without delay
Hope you can help. Thanks for your response Kind regards Halim
thanks,
Takashi