14 Dec
2002
14 Dec
'02
10:20 p.m.
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.