snd_pcm_open

Synopsis:

#include <sys/asoundlib.h>

int snd_pcm_open_name( snd_pcm_t **handle, 
                       char *name, 
                       int mode );

Arguments:

handle

A pointer to a location where snd_pcm_open_name() can store a handle for the audio interface. You'll need this handle when you call the other snd_pcm_* functions.

name

The name of the PCM device to open. Can be one of the following names (all found under /dev/snd):

a symbolic name (for example, pcmPreferredp, pcmPreferredc, or a name an io-audio option specifies).
a system-assigned name that identifies the card and device (for example, pcmC0D0c or pcmC0D0p; see Cards and devices in the “Audio Architecture” chapter).

mode

One of:

SND_PCM_OPEN_PLAYBACK — open the playback channel (direction).
SND_PCM_OPEN_CAPTURE — open the capture channel (direction).

You can OR the following flag with any of the above:

SND_PCM_OPEN_NONBLOCK — force the mode to be nonblocking. This affects any reading from or writing to the device that you do later; you can query the device any time without blocking.
You can change the blocking setup later by calling snd_pcm_nonblock_mode().

Library:

libasound.so

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

Description:

The snd_pcm_open_name() function creates a handle and opens a connection to the named PCM audio interface.

Using names for audio devices (snd_pcm_open_name()) is preferred to using numbers (snd_pcm_open()), although snd_pcm_open_preferred(). remains a good alternative to both.

Returns:

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

Errors:

-EINVAL: The state of handle is invalid, the mode is invalid, or an invalid state change occurred. You can call snd_pcm_channel_status() to check if the state change was invalid.
-ENOENT: The named device doesn't exist.
-ENOMEM: Not enough memory is available to allocate the control structures.
-SND_ERROR_INCOMPATIBLE_VERSION: The audio driver version is incompatible with the client library that the application is using.

Examples:

snd_pcm_open_name(&pcm_handle, "voice", SND_PCM_OPEN_CAPTURE);

See also the example of snd_pcm_open() in “ Opening your PCM device ” in the Playing and Capturing Audio Data chapter.

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.

Successfully opening a PCM channel doesn't guarantee that there are enough audio resources free to handle your application. Audio resources (e.g. subchannels) are allocated when you configure the channel by calling snd_pcm_channel_params() or snd_pcm_plugin_params() .