Re: [Alsa-user] Strange knocking while playing sound

2009-07-21 Thread Clemens Ladisch
Dennis Borgmann wrote:
 I am working with snd_pcm_mmap_begin and snd_pcm_mmap_commit - just the
 way it is done in the pcm.c under the test-directory of the
 alsa-lib. While working with snd_pcm_writei(), those problems did not
 occur, but I want to test this using the mmap technology.

This sounds like a problem with your mmap code.

As long as you are copying samples from some buffer into the sound
card's buffer, using mmap does not give you any benefit because this is
exactly the same as snd_pcm_writei() does.


Best regards,
Clemens

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[Alsa-user] Strange knocking while playing sound

2009-07-20 Thread Dennis Borgmann
Hello list-users!

I am programming some network-transmitting soundserver and client - I'm
tyring to get some soundstreaming via network done. Everything works
fine, the load of the driver ringbuffer seems to be OK so far (at least
400 frames in the buffer at any point of time, I am taking care of this
in my program). Although this seems to be right, I get some odd
knockings all of the time. The sound itself is transmitted OK, but
still there is this ugly noise in the background. If I set the volume of
the transmitting device to mute, the knocks go away and if I turn up
the volume of the playing device, the knocks become louder. So it goes
hand in hand with the music.

I am working with snd_pcm_mmap_begin and snd_pcm_mmap_commit - just the
way it is done in the pcm.c under the test-directory of the
alsa-lib. While working with snd_pcm_writei(), those problems did not
occur, but I want to test this using the mmap technology. (By the way,
this also leads me to the conclusion, that my problems are related to
the network client, which writes to the sound device). My problem does
not seem to be related to sepcific soundcards, as I saw the problem on
two different machines.

Any suggestions, what my problem might be?

Thanks a whole lot in advance for any kind of help!
Dennis

-


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