In ALSA PCM interface, two parameters are used for size of intermediate
buffer for data frames; period size and buffer size. Actual effects of
these sizes differs depending on hardware, but basically the size of
period is used for intervals of hardware interrupts and the size of buffer
is used to maintain the intermediate buffer as ring buffer. These
parameters can be configured as a part of hardware parameters by
data frame unit or micro second. PCM API in alsa-lib also includes
helper functions to configure them by the two units.
This commit adds support for options to the parameters by both units. When
no options are given, default values are applied according to current
aplay; available maximum size of buffer up to 500msec, a quarter of the
size of buffer for period size. However, these calculation should be
reconsidered somehow.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In aplay, '--test-nowait' is used to suppress calls of snd_pcm_wait()
when I/O operations return -EAGAIN or process truncated number of data
frames. This seems to be for debugging purpose. In this program, this
option is equivalent to suppress event waiting.
This commit adds support for this option.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In alsa-lib PCM API, data frames can be handled in mapped page frame,
instead of calling any system calls.
This commit support for 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 -M -P -d 2 -D hw:0,3 /dev/urandom -f dat -vvv
$ axfer transfer -M -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 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-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>
