On Wed, 3 Mar 2004, Michael Rausch wrote: > Hello! > My goal is to record speech from four different microphones (mono inputs) > and store it in correspondig four sound files. Then I should be able to > reproduce them simultaneously, in parallel on four outputs or mixed > together. > I'm quite new to both ecasound and alsa, and I have some problem. > My system is based on an AMD Athlon 2000+ with: > - on-board VIA 8235 sound card; > - one added M Audio Delta 66 sound card;
The problem with this setup is that the soundcards run on different clocks, so that even if they both support the same rate (say 44100) those two rates will not be the same. They can differ sometimes by rather significant amounts. So say one is 1% slow. That means it actually records only 40000 samples per second. Thus after 10 sec the two will be out of sync by 1/10 of a second. the "slower" card will be ahead of the "faster" on playback. also, all frequencies will be 1% (1/5 of a semitone) higher. to run such a multiple input system, you should have all of the inputs driven from the same clock-- that usually means all on the same card. You should at least test the two cards to see how far out they are from each other, so you know what to expect. (Then there is also the disconcerting behaviour of some cards, especially the Creative ones, to support only 48000 not 44100, so one of your cards could be running at 44100 samples/sec and the other at 48000.) This of course has nothing to do with your problem. ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Alsa-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-user
