[alsa-devel] [Pkg-alsa-devel] Bug#438118: alsa-utils: aplay non-blocking mode isn't working
anders at netinsight.se
Thu Sep 27 14:16:29 CEST 2007
>>>>> "TI" == Takashi Iwai <tiwai at suse.de> writes:
TI> At Tue, 18 Sep 2007 09:41:48 +0200 (CEST),
TI> Anders Boström wrote:
>> >>>>> "TI" == Takashi Iwai <tiwai at suse.de> writes:
>> >> can one please have a lokk at this? aplay -N isn't working for the
>> >> OP.
TI> Cannot reproduce here. Could you _post_ more details?
>> OK, I've tested more, and discovered that the problem seems to be that
>> the end of the sound is cut in non-blocking mode. And if I play a very
>> short sound-file, I can't hear anything. Blocking mode works fine.
>> When using non-blocking mode, an strace contains "ioctl(4, 0x4144,
>> 0x2b9f785d8000) = -1 EAGAIN (Resource temporarily
>> unavailable)". Blocking mode never contains the EAGAIN response.
>> I attach two files. When playing halt.au, I can only hear the start,
>> about as much as "ha". When playing metal.au, I can't hear anything.
TI> OK, thanks, I see the problem now.
TI> I don't remember whether it's a feature or a bug. The drain ioctl
TI> rejects the non-block mode.
I can understand the idea here, that in non-blocking mode, no call
should block, ever. But on the other hand, if you call the drain
ioctl, you probably expect it to work, even in non-blocking mode. Why
would you otherwise call it?
TI> Anyway, a simple patch is below. Let me know if it works.
It works fine! Thanks!
TI> diff -r 0028e39ead78 core/pcm_native.c
TI> --- a/core/pcm_native.c Tue Sep 18 00:52:38 2007 +0200
TI> +++ b/core/pcm_native.c Tue Sep 18 17:44:31 2007 +0200
TI> @@ -1368,8 +1368,6 @@ static int snd_pcm_prepare(struct snd_pc
TI> static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream, int state)
TI> - if (substream->f_flags & O_NONBLOCK)
TI> - return -EAGAIN;
substream-> runtime->trigger_master = substream;
TI> return 0;
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