At Tue, 28 Oct 2003 13:36:37 +0100 (CET), Jaroslav wrote: > > On Tue, 28 Oct 2003, Takashi Iwai wrote: > > > At Mon, 27 Oct 2003 13:11:58 +0100, > > Andreas Mohr wrote: > > > > > > Hello Takashi, > > > > > > On Mon, Oct 27, 2003 at 01:01:37PM +0100, Takashi Iwai wrote: > > > > At Sat, 25 Oct 2003 22:02:21 +0200, > > > > Andreas Mohr wrote: > > > > > Or, as a short summary: > > > > > The application is perfectly well aware of how many bytes there are left > > > > > to read (from calling SNDCTL_DSP_GETISPACE) and then does a read() with > > > > > this amount of bytes, however since the ALSA OSS layer attempts to read > > > > > this byte amount in blocks of runtime->oss.period_bytes bytes from the sound > > > > > device, we ARTIFICIALLY cause a -EAGAIN to be returned due to insufficient > > > > > available data, thus potentially confusing many OSS applications. > > > > > > > > > > Now what to do here? > > > > > > > > this problem is a bit touch, because the ALSA OSS layer does the > > > > sample-rate conversion, etc. > > > > when the sample rate is converted between 44.1kHz and 48kHz, some > > > > round error may happen and it will be accumulated. hence, the size > > > > will be different between two cases: reading a whole period once and > > > > reading a period by multiple calls. > > > > > > > > i'll take a more deeper look... > > > Ah, thanks! (also for the explanation given above) > > > > > > Given that 1.0 is approaching, it'd certainly be useful to get such a > > > problem fixed ;-) > > > > i come to believe that it's a bug, too. > > as you wrote, the fix is easy except for the rare problem what i > > mentioned above. in that case (e.g. the sample-rate conversion > > between 44.1 and 48khz required), you'll still get -EAGAIN > > occasionally. but normally, it seems ok. > > > > the attached is the patch to fix the original problem. > > to take back to the old behavior (always reading a whole period), > > you can write "whole-frag" command to the proc file. > > > > anyway, i'll try a bit more to solve the problem above. > > I think that the problem is at another place. I'm investigating the bug in > code now.
thanks. just to avoid confusion: there are two "bugs" here discussed. 1. the original problem, read() returns -EAGAIN when trying to read the bytes returned by GETISPACE ioctl. this is because snd_pcm_oss_read2() always reads a whole period. my last patch is for this problem. 2. read() return -EAGAIN occasionally. likely because of the rate plugin. Takashi ------------------------------------------------------- This SF.net email is sponsored by: The SF.net Donation Program. Do you like what SourceForge.net is doing for the Open Source Community? Make a contribution, and help us add new features and functionality. Click here: http://sourceforge.net/donate/ _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
