snd_pcm_playback

Play out all pending data in a PCM playback channel's queue and stop the channel

Synopsis:

#include <sys/asoundlib.h>

int snd_pcm_playback_flush( snd_pcm_t *handle);

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().

Library:

libasound.so

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

Description:

The snd_pcm_playback_flush() function blocks until all unprocessed data in the driver queue has been played.

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

Since this call is a blocking call, if the channel is in the SND_PCM_STATUS_SUSPENDED state an error occurs if you call this function. If you call this function while in the SND_PCM_STATUS_PAUSED state, playback is resumed and the channel goes into the SND_PCM_STATUS_RUNNING state immediately,and then ends in the SND_PCM_STATUS_READY state.

If the channel doesn't start playing (not enough data has been written to start playback), then this call silences the remainder of the buffer to satisfy the playback start requirements. Once the playback requirements are satisfied, playback starts and allows the data to be played out. Once the buffer empties, this call returns successfully.

If this call completes successfully, the channel is left in the SND_PCM_STATUS_READY state.

Note: This function isn't plugin-aware. It functions exactly the same way as snd_pcm_channel_flush(.., SND_PCM_CHANNEL_PLAYBACK). 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.

Returns:

EOK on success, a negative errno upon failure. The errno values are available in the errno.h file.

Errors:

Additional information for common error values:

-EAGAIN: The state was SND_PCM_STATUS_SUSPENDED while trying to call this function. This error is also returned if the state was SND_PCM_STATUS_PAUSED, but resuming the playback failed.
-EBADFD: The PCM device state isn't ready.
-EAGAIN: The PCM device state is in the SND_PCM_STATUS_SUSPENDED or SND_PCM_STATUS_PAUSED state.
-EINTR: The operation was interrupted because of a system signal (such as a timer) or an error was returned asynchronously.
-EINVAL: The state of handle is invalid or an invalid state change occurred. You can call snd_pcm_channel_status() to check if the state change was invalid.
-EIO: An invalid channel was specified, or the data wasn't all flushed.

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.