Hi, Haakmat, I'm so glad to see your reply. But I'm still wondering how I can implement the full duplex operation on sound card, i.e. playback and record audio on the same card at same time. I don't think it's a good idea that reopen the device when switch between reading and writting, because I found it sometime took much time to open the device and that means the quality wouldn't be good. Do u have another solution to it? Anybody have experience with it ? I really need suggestion about it and I also believe there must be some tricks which I havn't understood.
Thanks a lot anyway. This is my first question in this group and it's my pleasure to get your help. leo. --- Pascal Haakmat <[EMAIL PROTECTED]> wrote: > 13/12/02 15:46, leo zhu wrote: > > > Hi, guys, > > > > I am working on a project in which I need to > implement > > palyback and recording on the same sound card and > in > > the same time. > > > > I open the soundcard with RDWR mode and used > 'select' > > to wait for sound data on card and read it. After > > that, I receive audio data from socket and write > this > > data into buffer on card. for now. I tested it and > i > > found if just one way, ie. just read or write, it > > works fine, the quality of sound is fine. but if > two > > way, ie. play&record, the sound is horrible and > the > > weird is that I always get better sound quality > from > > playback that what i got from recording. (I heard > the > > audio from two ends). by the way, I used > > SNDCTL_DSP_TRIGGER to syncronyse them. > > > > can this method implement full-duplex functions ? > if > > not, what should I do? thanks in advance > > Yes, it's possible in principle, and it can work. > Although some > cards/drivers do it better than others... On Linux I > believe the > easiest way is to open the audio device twice: once > for reading and > once for writing. There might be other portability > problems with that > method as well. > I've never gotten SNDCTL_DSP_TRIGGER to work as > expected, but that may just have been impatience. __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com
