- struct aout_sys_t *sys; /**< Output plugin private data */
- int (*start) (audio_output_t *, audio_sample_format_t *);
- void (*stop) (audio_output_t *);
- void (*play)(audio_output_t *, block_t *, mtime_t *); /**< Play callback
- - queue a block for playback */
- void (*pause)( audio_output_t *, bool, mtime_t ); /**< Pause/resume
- callback (optional, may be NULL) */
- void (*flush)( audio_output_t *, bool ); /**< Flush/drain callback
- (optional, may be NULL) */
- int (*volume_set)(audio_output_t *, float); /**< Volume setter (or NULL) */
- int (*mute_set)(audio_output_t *, bool); /**< Mute setter (or NULL) */
-
+ struct aout_sys_t *sys; /**< Private data for callbacks */
+
+ int (*start)(audio_output_t *, audio_sample_format_t *fmt);
+ /**< Starts a new stream (mandatory, cannot be NULL).
+ * \param fmt input stream sample format upon entry,
+ * output stream sample format upon return [IN/OUT]
+ * \return VLC_SUCCESS on success, non-zero on failure
+ * \note No other stream may be already started when called.
+ */
+ void (*stop)(audio_output_t *);
+ /**< Stops the existing stream (optional, may be NULL).
+ * \note A stream must have been started when called.
+ */
+ int (*time_get)(audio_output_t *, mtime_t *delay);
+ /**< Estimates playback buffer latency (optional, may be NULL).
+ * \param delay pointer to the delay until the next sample to be written
+ * to the playback buffer is rendered [OUT]
+ * \return 0 on success, non-zero on failure or lack of data
+ * \note A stream must have been started when called.
+ */
+ void (*play)(audio_output_t *, block_t *);
+ /**< Queues a block of samples for playback (mandatory, cannot be NULL).
+ * \note A stream must have been started when called.
+ */
+ void (*pause)( audio_output_t *, bool pause, mtime_t date);
+ /**< Pauses or resumes playback (optional, may be NULL).
+ * \param pause pause if true, resume from pause if false
+ * \param date timestamp when the pause or resume was requested
+ * \note A stream must have been started when called.
+ */
+ void (*flush)( audio_output_t *, bool wait);
+ /**< Flushes or drains the playback buffers (mandatory, cannot be NULL).
+ * \param wait true to wait for playback of pending buffers (drain),
+ * false to discard pending buffers (flush)
+ * \note A stream must have been started when called.
+ */
+ int (*volume_set)(audio_output_t *, float volume);
+ /**< Changes playback volume (optional, may be NULL).
+ * \param volume requested volume (0. = mute, 1. = nominal)
+ * \note The volume is always a positive number.
+ * \warning A stream may or may not have been started when called.
+ */
+ int (*mute_set)(audio_output_t *, bool mute);
+ /**< Changes muting (optinal, may be NULL).
+ * \param mute true to mute, false to unmute
+ * \warning A stream may or may not have been started when called.
+ */
+ int (*device_select)(audio_output_t *, const char *id);
+ /**< Selects an audio output device (optional, may be NULL).
+ * \param id nul-terminated device unique identifier.
+ * \return 0 on success, non-zero on failure.
+ * \warning A stream may or may not have been started when called.
+ */