Transfer PCM data to playback channel
#include <sys/asoundlib.h> ssize_t snd_pcm_write( snd_pcm_t *handle, const void *buffer, size_t size );
libasound.so
The snd_pcm_write() function writes samples to the device, which must be in the proper format specified by snd_pcm_channel_prepare() or snd_pcm_playback_prepare().
This function may suspend a process if blocking mode is active (see snd_pcm_nonblock_mode()). and no space is available in the device's buffers.
When the subdevice is in blocking mode (SND_PCM_MODE_BLOCK), then the number of written bytes must fulfill the N × fragment-size expression, where N > 0.
If the stream format is noninterleaved (the interleave member of the snd_pcm_format_t structure isn't set), then the driver expects that data in one fragment is separated to single voice blocks. For example, imagine that you have two voices, and the fragment size is 512 bytes. The number of bytes per one voice is 256. The driver expects that the first 256 bytes contain samples for the first voice and the second 256 bytes from fragment contain samples for the second voice.
A positive value that represents the number of bytes that were successfully written to the device if the playback was successful, or an error value if an error occurred.
QNX Neutrino
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |
snd_pcm_channel_prepare(), snd_pcm_playback_prepare(), snd_pcm_plugin_write()