diff options
Diffstat (limited to 'src/xine-engine/audio_out.c')
| -rw-r--r-- | src/xine-engine/audio_out.c | 67 |
1 files changed, 51 insertions, 16 deletions
diff --git a/src/xine-engine/audio_out.c b/src/xine-engine/audio_out.c index 27dc57dfb..52e568339 100644 --- a/src/xine-engine/audio_out.c +++ b/src/xine-engine/audio_out.c @@ -17,7 +17,7 @@ * along with self program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * - * $Id: audio_out.c,v 1.48 2002/03/19 02:12:49 guenter Exp $ + * $Id: audio_out.c,v 1.49 2002/03/26 01:47:17 miguelfreitas Exp $ * * 22-8-2001 James imported some useful AC3 sections from the previous alsa driver. * (c) 2001 Andy Lo A Foe <andy@alsaplayer.org> @@ -76,6 +76,32 @@ #define ZERO_BUF_SIZE 5000 +/* By adding gap errors (difference between reported and expected + * sound card clock) into metronom's vpts_offset we can use its + * smoothing algorithms to correct sound card clock drifts. + * obs: previously this error was added to xine scr. + * + * audio buf ---> metronom --> audio fifo --> (buf->vpts - hw_vpts) + * (vpts_offset + error) gap + * <---------- control --------------| + * + * Unfortunately audio fifo adds a large delay to our closed loop. + * + * These are designed to avoid updating the metronom too fast. + * - it will only be updated 1 time per second (so it has a chance of + * distributing the error for several frames). + * - it will only be updated 2 times for the whole audio fifo size + * length (so the control will wait to see the feedback effect) + * - each update will be of gap/SYNC_GAP_RATE. + * + * Sound card clock correction can only provide smooth playback for + * errors < 1% nominal rate. For bigger errors (bad streams) audio + * buffers may be dropped or gaps filled with silence. + */ +#define SYNC_TIME_INVERVAL (1 * 90000) +#define SYNC_BUF_INTERVAL NUM_AUDIO_BUFFERS / 2 +#define SYNC_GAP_RATE 4 + struct audio_fifo_s { audio_buffer_t *first; audio_buffer_t *last; @@ -240,12 +266,16 @@ static void *ao_loop (void *this_gen) { int64_t cur_time; int num_output_frames ; int paused_wait; + int64_t last_sync_time; + int bufs_since_sync; - + last_sync_time = bufs_since_sync = 0; + while ((this->audio_loop_running) || (!this->audio_loop_running && this->out_fifo->first)) { buf = fifo_remove (this->out_fifo); + bufs_since_sync++; do { delay = this->driver->delay(this->driver); @@ -294,8 +324,8 @@ static void *ao_loop (void *this_gen) { /* * output audio data synced to master clock */ - - if (gap < (-1 * this->gap_tolerance) || !buf->num_frames || + + if (gap < (-1 * AO_MAX_GAP) || !buf->num_frames || this->audio_paused ) { /* drop package */ @@ -306,19 +336,24 @@ static void *ao_loop (void *this_gen) { #endif } else { - - if (gap>this->gap_tolerance) { - - if (gap>15000) - ao_fill_gap (this, gap); - else { - printf ("audio_out: adjusting master clock %lld -> %lld\n", - cur_time, cur_time + gap); - this->metronom->adjust_clock (this->metronom, - cur_time + gap); - } - } + /* for small gaps ( tolerance < abs(gap) < AO_MAX_GAP ) + * feedback them into metronom's vpts_offset. + */ + if ( abs(gap) < AO_MAX_GAP && abs(gap) > this->gap_tolerance && + cur_time > (last_sync_time + SYNC_TIME_INVERVAL) && + bufs_since_sync >= SYNC_BUF_INTERVAL ) { + + this->metronom->set_option(this->metronom, METRONOM_ADJ_VPTS_OFFSET, + -gap/SYNC_GAP_RATE ); + last_sync_time = cur_time; + bufs_since_sync = 0; + } + + /* for big gaps output silence */ + if ( gap > AO_MAX_GAP ) { + ao_fill_gap (this, gap/2); + } /* * resample and output audio data |