Sample Cache

Overview

The sample cache provides a simple way of overcoming high network latencies and reducing bandwidth. Instead of streaming a sound precisely when it should be played, it is stored on the server and only the command to start playing it needs to be sent.

Creation

To create a sample, the normal stream API is used (see Audio Streams). The function pa_stream_connect_upload() will make sure the stream is stored as a sample on the server.

To complete the upload, pa_stream_finish_upload() is called and the sample will receive the same name as the stream. If the upload should be aborted, simply call pa_stream_disconnect().

Playing samples

To play back a sample, simply call pa_context_play_sample():

pa_operation *o;
 
o = pa_context_play_sample(my_context,
                           "sample2",       // Name of my sample
                           NULL,            // Use default sink
                           PA_VOLUME_NORM,  // Full volume
                           NULL,            // Don't need a callback
                           NULL
                           );
if (o)
    pa_operation_unref(o);

Removing samples

When a sample is no longer needed, it should be removed on the server to save resources. The sample is deleted using pa_context_remove_sample().