snd_pcm_plugin

Finish processing all pending data in a PCM channel's queue and stop the channel

Synopsis:

#include <sys/asoundlib.h>

int snd_pcm_plugin_flush( snd_pcm_t *handle, 
                          int        channel );

Arguments:

handle: The handle for the PCM device, which you must have opened by calling snd_pcm_open_name(), snd_pcm_open(), or snd_pcm_open_preferred().
channel: The channel; SND_PCM_CHANNEL_CAPTURE or SND_PCM_CHANNEL_PLAYBACK.

Library:

libasound.so

Use the -l asound option to qcc to link against this library.

Description:

The snd_pcm_plugin_flush() function flushes all unprocessed data in the driver queue:

If the plugin is processing playback data, the call blocks until all data in the driver queue is played out the channel.
If the plugin is processing capture data, any unread data in the driver queue is discarded.

If the operation is successful (zero is returned), the channel's state is changed to SND_PCM_STATUS_READY.

Returns:

A positive number on success, or a negative value on error.

Errors:

-EINVAL: The state of handle is invalid, an invalid channel was provided as input,or an invalid state change occurred. You can call snd_pcm_plugin_status() to check if the state change was invalid.
-EINTR: The operation was interrupted because of a system signal (such as a timer) or an error was returned asynchronously

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Read the Caveats

Caveats:

This function is not thread safe if handle (snd_pcm_t) is used across multiple threads.

Because the plugin interface may be subbuffering the written data until a complete driver block can be assembled, the flush call may have to inject up to (blocksize-1) samples into the channel so that the last block can be sent to the driver for playing. For this reason, the flush call may return a positive value indicating that this silence had to be inserted.

This function is the plugin-aware version of snd_pcm_channel_flush() . It functions exactly the same way, with the above caveat. However, make sure that you don't mix and match plugin- and nonplugin-aware functions in your application, or you may get undefined behavior and misleading results.