Set the link mode for a subchannel in a group
Synopsis:
#include <sys/asoundlib.h>
int snd_pcm_link_mode(snd_pcm_t *handle, int mode);
Arguments:
- handle
- A handle to the subchannel in the PCM group.
- mode
- he behavior of how calls to one thread impact the other subchannels in the same group. You can use one of the following modes:
- SND_PCM_LINK_MODE_SYNC—(Default)
The subchannels in the group synchronize together to respond
to a call made to a subchannel in the group.
For example, if you call snd_pcm_*_resume()
on one subchannel in the group, the other subchannels
in the group respond to the snd_pcm_*_resume()
call and transition to the RUNNING state.
- SND_PCM_LINK_MODE_ASYNC—For audio
concurrency management purposes, the subchannels that are grouped
together are treated as a single audio stream, but synchronization
of the calls made to a subchannel in the group won't occur. For
example, if you call snd_pcm_*_resume(), only the
specified subchannel resumes playing.
- SND_PCM_LINK_MODE_TRANSITION—Start
playback on the PCM handles in the group
that have this mode set when the current
PCM handle's buffer is empty.
Library:
libasound.so
Use the -l asound option with
qcc
to link against this library.
Description:
The snd_pcm_link_mode() function sets the link mode for subchannel in a
group. Within the group, you can configure different subchannels to have different modes
—in other words, you can mix the modes that are set on different PCM handles
belonging to the same group. For example, if you have a group of four subchannels,
you could set the mode of three of them to SND_PCM_LINK_MODE_SYNC
and the remaining subchannel to SND_PCM_LINK_MODE_ASYNC.
Returns:
EOK on success, or an errno value if an error occurred.
Errors:
- -EINVAL
- Failed to change the link mode because of either an invalid handle
to a PCM group or the application tried to set the link mode
for a subchannel that's used to capture audio.
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 is used across multiple threads.