In alsa-lib PCM API, snd_pcm_read[i|n]() and snd_pcm_write[i|n] can be
used with non-blocking mode. This is available when SND_PCM_NONBLOCK is
used as 'mode' argument for a call of snd_pcm_open().
This commit adds support this type of operation. To reduce CPU usage, this
commit uses 'snd_pcm_wait()' to wait for event notification.
Below lines are examples to execute:
$ axfer transfer -N -P -d 2 -D hw:0,3 /dev/urandom -f dat -vvv
$ axfer transfer -N -C -d 2 -D hw:1,0 /dev/null -r 48000 -vvv
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In aplay, '--fatal-errors' option has an effect to give up recovery of PCM
substream from XRUN state. This commit adds support for this option.
In original implementation, this option brings program abort. This seems
to generate core dump of process VMA. However, typically, XRUN comes from
timing mismatch between hardware and application, therefore core dump has
less helpful. This commit finishes this program in usual way with this
option at XRUN.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In ALSA PCM interface, before configuring hardware actually, applications
can request available set of hardware parameters for runtime of PCM
substream. The set of parameters are represented and delivered by a
structure.
In alsa-lib PCM API, the above design is abstracted by a series of
snd_pcm_hw_params_xxx() functions. An actual layout of the structure is
hidden from applications by an opaque pointer.
In aplay, '--dump-hw-params' option is for this purpose. With this option,
the command output available set of the hardware parameters.
This commit adds support for the option. Unlike aplay, this commit takes
this program to finish after dumping the parameters for simplicity of
usage.
I note that all of combinations in the set are not necessarily available
when the PCM substream includes dependencies of parameters described by
constraints and rules.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In alsa-lib PCM API, snd_pcm_read[i|n]() and snd_pcm_write[i|n]() are used
to transfer data frames from/to hardware. When a handler is not opened with
specific flags, these functions perform blocking operation; i.e. the
function call doesn't return till all of request number of data frames are
actually handled, or call is interrupted by Unix signals, or PCM substeam
corrupts due to hardware reasons.
This commit adds support for this type of data transmission. For cases that
requested data frames are not processed by container interface, this commit
adds internal cache mechanism to handle rest of data frames in next timing.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit adds support fo alsa-lib PCM API as a backend of 'xfer'
module. In a set of alsa-lib PCM API, there're two ways to handle data
frames; by calling ioctl(2) with some specific commands with buffer in
user space, or copying data frames on mapped page frames. To support
both ways, this commit adds an operation structure as abstraction.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
