path: root/src/xine-engine/metronom.c

/*
 * Copyright (C) 2000-2003 the xine project
 *
 * This file is part of xine, a free video player.
 *
 * xine is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * xine is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <time.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <string.h>
#include <errno.h>

#define LOG_MODULE "metronom"
#define LOG_VERBOSE
/*
#define LOG
#define LOG_AUDIO
*/
#define METRONOM_INTERNAL
#define METRONOM_CLOCK_INTERNAL

#include "xine_internal.h"
#include "metronom.h"
#include "xineutils.h"

#define MAX_AUDIO_DELTA        1600
#define AUDIO_SAMPLE_NUM      32768
#define WRAP_THRESHOLD       120000
#define MAX_NUM_WRAP_DIFF        10
#define MAX_SCR_PROVIDERS        10
#define VIDEO_DRIFT_TOLERANCE 45000
#define AUDIO_DRIFT_TOLERANCE 45000

/* metronom video modes */
#define VIDEO_PREDICTION_MODE     0      /* use pts + frame duration */
#define VIDEO_PTS_MODE            1      /* use only pts */

/* redefine abs as macro to handle 64-bit diffs.
   i guess llabs may not be available everywhere */
#define abs(x) ( ((x)<0) ? -(x) : (x) )


/*
 * ****************************************
 *   primary SCR plugin:
 *    unix System Clock Reference
 * ****************************************
 */

typedef struct unixscr_s {
  scr_plugin_t     scr;

  struct timeval   cur_time;
  int64_t         cur_pts;
  double           speed_factor;

  pthread_mutex_t  lock;

} unixscr_t;

static int unixscr_get_priority (scr_plugin_t *scr) {
  return 5; /* low priority */
}

/* Only call this when already mutex locked */
static void unixscr_set_pivot (unixscr_t *this) {

  struct   timeval tv;
  int64_t pts;
  double   pts_calc;

  xine_monotonic_clock(&tv, NULL);
  pts_calc = (tv.tv_sec  - this->cur_time.tv_sec) * this->speed_factor;
  pts_calc += (tv.tv_usec - this->cur_time.tv_usec) * this->speed_factor / 1e6;
  pts = this->cur_pts + pts_calc;

/* This next part introduces a one off inaccuracy
 * to the scr due to rounding tv to pts.
 */
  this->cur_time.tv_sec=tv.tv_sec;
  this->cur_time.tv_usec=tv.tv_usec;
  this->cur_pts=pts;

  return ;
}

static int unixscr_set_speed (scr_plugin_t *scr, int speed) {
  unixscr_t *this = (unixscr_t*) scr;

  pthread_mutex_lock (&this->lock);

  unixscr_set_pivot( this );
  this->speed_factor = (double) speed * 90000.0 / XINE_FINE_SPEED_NORMAL;

  pthread_mutex_unlock (&this->lock);

  return speed;
}

static void unixscr_adjust (scr_plugin_t *scr, int64_t vpts) {
  unixscr_t *this = (unixscr_t*) scr;
  struct   timeval tv;

  pthread_mutex_lock (&this->lock);

  xine_monotonic_clock(&tv, NULL);
  this->cur_time.tv_sec=tv.tv_sec;
  this->cur_time.tv_usec=tv.tv_usec;
  this->cur_pts = vpts;

  pthread_mutex_unlock (&this->lock);
}

static void unixscr_start (scr_plugin_t *scr, int64_t start_vpts) {
  unixscr_t *this = (unixscr_t*) scr;

  pthread_mutex_lock (&this->lock);

  xine_monotonic_clock(&this->cur_time, NULL);
  this->cur_pts = start_vpts;

  pthread_mutex_unlock (&this->lock);

  unixscr_set_speed (&this->scr, XINE_FINE_SPEED_NORMAL);
}

static int64_t unixscr_get_current (scr_plugin_t *scr) {
  unixscr_t *this = (unixscr_t*) scr;

  struct   timeval tv;
  int64_t pts;
  double   pts_calc;
  pthread_mutex_lock (&this->lock);

  xine_monotonic_clock(&tv, NULL);

  pts_calc = (tv.tv_sec  - this->cur_time.tv_sec) * this->speed_factor;
  pts_calc += (tv.tv_usec - this->cur_time.tv_usec) * this->speed_factor / 1e6;

  pts = this->cur_pts + pts_calc;

  pthread_mutex_unlock (&this->lock);

  return pts;
}

static void unixscr_exit (scr_plugin_t *scr) {
  unixscr_t *this = (unixscr_t*) scr;

  pthread_mutex_destroy (&this->lock);
  free(this);
}

static scr_plugin_t *XINE_MALLOC unixscr_init () {
  unixscr_t *this;

  this = calloc(1, sizeof(unixscr_t));

  this->scr.interface_version = 3;
  this->scr.get_priority      = unixscr_get_priority;
  this->scr.set_fine_speed    = unixscr_set_speed;
  this->scr.adjust            = unixscr_adjust;
  this->scr.start             = unixscr_start;
  this->scr.get_current       = unixscr_get_current;
  this->scr.exit              = unixscr_exit;

  pthread_mutex_init (&this->lock, NULL);

  unixscr_set_speed (&this->scr, XINE_SPEED_PAUSE);
  lprintf("xine-scr_init complete\n");

  return &this->scr;
}


/*
 * ****************************************
 *       master clock feature
 * ****************************************
 */


static void metronom_start_clock (metronom_clock_t *this, int64_t pts) {
  scr_plugin_t** scr;

  lprintf("start_clock (at %" PRId64 ")\n", pts);

  for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
    if (*scr) (*scr)->start(*scr, pts);

  this->speed = XINE_FINE_SPEED_NORMAL;
}


static int64_t metronom_get_current_time (metronom_clock_t *this) {
  return this->scr_master->get_current(this->scr_master);
}


static void metronom_stop_clock(metronom_clock_t *this) {
  scr_plugin_t** scr;
  for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
    if (*scr) (*scr)->set_fine_speed(*scr, XINE_SPEED_PAUSE);
}

static void metronom_resume_clock(metronom_clock_t *this) {
  scr_plugin_t** scr;
  for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
    if (*scr) (*scr)->set_fine_speed(*scr, XINE_FINE_SPEED_NORMAL);
}



static void metronom_adjust_clock(metronom_clock_t *this, int64_t desired_pts) {
  if (this->scr_adjustable)
    this->scr_master->adjust(this->scr_master, desired_pts);
}

static int metronom_set_speed (metronom_clock_t *this, int speed) {

  scr_plugin_t **scr;
  int            true_speed;

  true_speed = this->scr_master->set_fine_speed (this->scr_master, speed);

  this->speed = true_speed;

  for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
    if (*scr) (*scr)->set_fine_speed(*scr, true_speed);

  return true_speed;
}


static void metronom_set_audio_rate (metronom_t *this, int64_t pts_per_smpls) {
  pthread_mutex_lock (&this->lock);

  this->pts_per_smpls = pts_per_smpls;

  pthread_mutex_unlock (&this->lock);

  lprintf("%" PRId64 " pts per %d samples\n", pts_per_smpls, AUDIO_SAMPLE_NUM);
}

static int64_t metronom_got_spu_packet (metronom_t *this, int64_t pts) {
  int64_t vpts;

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    metronom_t *master = this->master;

    pthread_mutex_lock(&this->master->lock);
    pthread_mutex_unlock(&this->lock);

    this->vpts_offset = this->master->vpts_offset;
    this->spu_offset  = this->master->spu_offset;

    /* no recursion, please */
    this->master = NULL;
    vpts = master->got_spu_packet(this, pts);
    this->master = master;

    pthread_mutex_unlock(&this->master->lock);
    return vpts;
  }

  vpts = pts + this->vpts_offset + this->spu_offset;

  /* no vpts going backwards please */
  if( vpts < this->spu_vpts )
    vpts = this->spu_vpts;

  this->spu_vpts = vpts;

  pthread_mutex_unlock (&this->lock);
  return vpts;
}

static void metronom_handle_discontinuity (metronom_t *this, int type,
                                           int64_t disc_off) {
  int64_t cur_time;

  /* video_vpts and audio_vpts adjustements */
  cur_time = this->xine->clock->get_current_time(this->xine->clock);

  switch (type) {
    case DISC_STREAMSTART:
    case DISC_STREAMSEEK:
      this->video_vpts = this->prebuffer + cur_time;
      this->audio_vpts = this->video_vpts;
      this->audio_vpts_rmndr = 0;
      this->force_audio_jump = 1;
      this->force_video_jump = 1;
      this->video_drift = 0;
      xprintf(this->xine, XINE_VERBOSITY_DEBUG,
	      "vpts adjusted with prebuffer to %" PRId64 "\n", this->video_vpts);
      break;

    case DISC_ABSOLUTE:
    case DISC_RELATIVE:
      if (this->video_vpts < cur_time) {
        /* still frame */
        if (this->audio_vpts > cur_time) {
          /* still frame with audio */
          this->video_vpts = this->audio_vpts;
          xprintf(this->xine, XINE_VERBOSITY_DEBUG, "video vpts adjusted to audio vpts %" PRId64 "\n", this->video_vpts);
        } else {
          /* still frame, no audio */
          this->video_vpts = this->prebuffer + cur_time;
          this->audio_vpts = this->video_vpts;
          this->audio_vpts_rmndr = 0;
          this->force_video_jump = 1;
          this->force_audio_jump = 1;
          this->video_drift = 0;
          xprintf(this->xine, XINE_VERBOSITY_DEBUG, "vpts adjusted with prebuffer to %" PRId64 "\n",
	    this->video_vpts);
        }
      } else {
        /* video */
        if (this->audio_vpts < cur_time) {
          /* video, no sound */
          this->audio_vpts = this->video_vpts;
          this->audio_vpts_rmndr = 0;
          xprintf(this->xine, XINE_VERBOSITY_DEBUG, "audio vpts adjusted to video vpts %" PRId64 "\n", this->video_vpts);
        } else {
          /* video + audio */
        }
      }
      break;
  }

  lprintf("video_vpts: %" PRId64 ", audio_vpts: %" PRId64 "\n", this->video_vpts, this->audio_vpts);

  /* vpts_offset adjustements */
  switch (type) {
  case DISC_STREAMSTART:
    lprintf("DISC_STREAMSTART\n");
    this->vpts_offset = this->video_vpts;
    break;
  case DISC_ABSOLUTE:
    lprintf("DISC_ABSOLUTE\n");
    this->vpts_offset = this->video_vpts - disc_off;
    break;
  case DISC_RELATIVE:
    lprintf("DISC_RELATIVE\n");
    this->vpts_offset = this->vpts_offset - disc_off;
    break;
  case DISC_STREAMSEEK:
    lprintf("DISC_STREAMSEEK\n");
    this->vpts_offset = this->video_vpts - disc_off;
    break;
  }
  
  this->last_video_pts = 0;
  this->last_audio_pts = 0;
}

static void metronom_handle_video_discontinuity (metronom_t *this, int type,
						 int64_t disc_off) {

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    /* slaves are currently not allowed to set discontinuities */
    pthread_mutex_unlock(&this->lock);
    return;
  }

  this->video_discontinuity_count++;
  pthread_cond_signal (&this->video_discontinuity_reached);

  xprintf(this->xine, XINE_VERBOSITY_DEBUG, "video discontinuity #%d, type is %d, disc_off %" PRId64 "\n",
    this->video_discontinuity_count, type, disc_off);

  if (this->have_audio) {
    while (this->audio_discontinuity_count <
	   this->video_discontinuity_count) {

      xprintf(this->xine, XINE_VERBOSITY_DEBUG, "waiting for audio discontinuity #%d\n",
        this->video_discontinuity_count);

      pthread_cond_wait (&this->audio_discontinuity_reached, &this->lock);
    }
  }

  metronom_handle_discontinuity(this, type, disc_off);

  this->discontinuity_handled_count++;
  pthread_cond_signal (&this->video_discontinuity_reached);

  pthread_mutex_unlock (&this->lock);
}

static void metronom_got_video_frame (metronom_t *this, vo_frame_t *img) {

  int64_t vpts;
  int64_t pts = img->pts;
  int64_t diff;

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    metronom_t *master = this->master;

    pthread_mutex_lock(&this->master->lock);
    pthread_mutex_unlock(&this->lock);

    if (!this->discontinuity_handled_count) {
      /* we are not initialized yet */
      if (this->master->video_vpts > this->master->audio_vpts)
        this->video_vpts = this->audio_vpts = this->master->video_vpts;
      else
        this->video_vpts = this->audio_vpts = this->master->audio_vpts;
      /* when being attached to the first master, do not drift into
       * his vpts values but adopt at once */
      this->force_audio_jump = 1;
      this->force_video_jump = 1;
      this->discontinuity_handled_count++;
    }

    this->vpts_offset = this->master->vpts_offset;
    this->av_offset   = this->master->av_offset;

    /* no recursion, please */
    this->master = NULL;
    master->got_video_frame(this, img);
    this->master = master;

    pthread_mutex_unlock(&this->master->lock);
    return;
  }

  lprintf("got_video_frame pts = %" PRId64 ", duration = %d\n", pts, img->duration);

  this->img_cpt++;

  if (img->duration) {
    this->video_mode = VIDEO_PREDICTION_MODE;
    this->img_duration = img->duration;
  } else {
    /* will skip the whole predicted vpts stuff */
    this->video_mode = VIDEO_PTS_MODE;
  }

  if (pts && pts != this->last_video_pts) {

    if (!img->duration) {
      /* Compute the duration of previous frames using this formula:
       * duration = (curent_pts - last_pts) / (frame count between the 2 pts)
       * This duration will be used to predict the next frame vpts.
       */
      if (this->last_video_pts && this->img_cpt) {
        this->img_duration = (pts - this->last_video_pts) / this->img_cpt;
        lprintf("computed frame_duration = %" PRId64 "\n", this->img_duration );
      }
    }
    this->img_cpt = 0;
    this->last_video_pts = pts;


    /*
     * compare predicted (this->video_vpts) and given (pts+vpts_offset)
     * pts values - hopefully they will be the same
     * if not, for small diffs try to interpolate
     *         for big diffs: jump
     */

    vpts = pts + this->vpts_offset;

    if (this->video_mode == VIDEO_PREDICTION_MODE) {

      diff = this->video_vpts - vpts;

      lprintf("video diff is %" PRId64 " (predicted %" PRId64 ", given %" PRId64 ")\n", diff, this->video_vpts, vpts);


      if ((abs (diff) > VIDEO_DRIFT_TOLERANCE) || (this->force_video_jump)) {
        this->force_video_jump = 0;
        this->video_vpts       = vpts;
        this->video_drift      = 0;

        xprintf(this->xine, XINE_VERBOSITY_DEBUG, "video jump\n");

      } else {

        this->video_drift = diff;
        this->video_drift_step = diff / 30;
        /* this will fix video drift with a constant compensation each
	 frame for about 1 second of video.  */

        if (diff) lprintf("video drift, drift is %" PRId64 "\n", this->video_drift);
      }
    } else {
      /* VIDEO_PTS_MODE: do not use the predicted value */
      this->video_vpts = vpts;
    }
  }

  img->vpts = this->video_vpts + this->av_offset;

  if (this->video_mode == VIDEO_PREDICTION_MODE) {
    lprintf("video vpts for %10"PRId64" : %10"PRId64" (duration:%d drift:%" PRId64 " step:%" PRId64 ")\n",
	  pts, this->video_vpts, img->duration, this->video_drift, this->video_drift_step );

    if (this->video_drift * this->video_drift_step > 0) {
      img->duration -= this->video_drift_step;
      this->img_duration = img->duration;
      this->video_drift -= this->video_drift_step;
    }
  }

  /* We need to update this->video_vpts is both modes.
   * this->video_vpts is used as the next frame vpts if next frame pts=0
   */
  this->video_vpts += this->img_duration;

  pthread_mutex_unlock (&this->lock);
}

static void metronom_handle_audio_discontinuity (metronom_t *this, int type,
						 int64_t disc_off) {

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    /* slaves are currently not allowed to set discontinuities */
    pthread_mutex_unlock(&this->lock);
    return;
  }

  this->audio_discontinuity_count++;
  pthread_cond_signal (&this->audio_discontinuity_reached);

  xprintf(this->xine, XINE_VERBOSITY_DEBUG, "audio discontinuity #%d, type is %d, disc_off %" PRId64 "\n",
	  this->audio_discontinuity_count, type, disc_off);

  if (this->have_video) {

    /* next_vpts_offset, in_discontinuity is handled in expect_video_discontinuity */
    while ( this->audio_discontinuity_count >
            this->discontinuity_handled_count ) {

      xprintf(this->xine, XINE_VERBOSITY_DEBUG, "waiting for in_discontinuity update #%d\n",
	      this->audio_discontinuity_count);

      pthread_cond_wait (&this->video_discontinuity_reached, &this->lock);
    }
  } else {
    metronom_handle_discontinuity(this, type, disc_off);
  }

  this->audio_samples = 0;
  this->audio_drift_step = 0;

  pthread_mutex_unlock (&this->lock);
}

static int64_t metronom_got_audio_samples (metronom_t *this, int64_t pts,
					   int nsamples) {

  int64_t vpts;
  int64_t diff;

  lprintf("got %d audio samples, pts is %" PRId64 ", last pts = %" PRId64 "\n", nsamples, pts, this->last_audio_pts);
  lprintf("AUDIO pts from last= %" PRId64 "\n", pts-this->last_audio_pts);

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    metronom_t *master = this->master;

    pthread_mutex_lock(&this->master->lock);
    pthread_mutex_unlock(&this->lock);

    if (!this->discontinuity_handled_count) {
      /* we are not initialized yet */
      if (this->master->video_vpts > this->master->audio_vpts)
        this->video_vpts = this->audio_vpts = this->master->video_vpts;
      else
        this->video_vpts = this->audio_vpts = this->master->audio_vpts;
      this->audio_vpts_rmndr = 0;
      /* when being attached to the first master, do not drift into
       * his vpts values but adopt at once */
      this->force_audio_jump = 1;
      this->force_video_jump = 1;
      this->discontinuity_handled_count++;
    }

    this->vpts_offset = this->master->vpts_offset;

    /* no recursion, please */
    this->master = NULL;
    vpts = master->got_audio_samples(this, pts, nsamples);
    this->master = master;

    pthread_mutex_unlock(&this->master->lock);
    return vpts;
  }

  if (pts && pts != this->last_audio_pts) {
    vpts = pts + this->vpts_offset;
    diff = this->audio_vpts - vpts;
    this->last_audio_pts = pts;

    /* compare predicted and given vpts */
    if((abs(diff) > AUDIO_DRIFT_TOLERANCE) || (this->force_audio_jump)) {
      this->force_audio_jump = 0;
      this->audio_vpts       = vpts;
      this->audio_vpts_rmndr = 0;
      this->audio_drift_step = 0;
      xprintf(this->xine, XINE_VERBOSITY_DEBUG, "audio jump, diff=%" PRId64 "\n", diff);
    } else {
      if( this->audio_samples ) {
        /* calculate drift_step to recover vpts errors */
        lprintf("audio diff = %" PRId64 " \n", diff );

        diff *= AUDIO_SAMPLE_NUM;
        diff /= this->audio_samples * 4;

        /* drift_step is not allowed to change rate by more than 25% */
        if( diff > this->pts_per_smpls/4 )
          diff = this->pts_per_smpls/4;
        if( diff < -this->pts_per_smpls/4 )
          diff = -this->pts_per_smpls/4;

        this->audio_drift_step = diff;

        lprintf("audio_drift = %" PRId64 ", pts_per_smpls = %" PRId64 "\n", diff, this->pts_per_smpls);
      }
    }
    this->audio_samples = 0;
  }
  vpts = this->audio_vpts;

  /* drift here is caused by streams where nominal sample rate differs from
   * the rate of which pts increments. fixing the audio_vpts won't do us any
   * good because sound card won't play it faster or slower just because
   * we want. however, adding the error to the vpts_offset will force video
   * to change it's frame rate to keep in sync with us.
   *
   * Since we are using integer division below, it can happen that we lose
   * precision for the calculated duration in vpts for each audio buffer
   * (< 1 PTS, e.g. 0.25 PTS during playback of most DVDs with LPCM audio).
   * This would lead to a situation where the sound card actually needs
   * more time to play back the buffers, than the audio buffer's vpts field
   * indicates. This makes audio_out loop think we are in sync with the
   * soundcard, while we actually are not. So that's why there is the extra
   * modulo calculation, to keep track of the truncated, fractional part.
   */
  this->audio_vpts_rmndr += nsamples * this->pts_per_smpls % AUDIO_SAMPLE_NUM;
  this->audio_vpts       += nsamples * this->pts_per_smpls / AUDIO_SAMPLE_NUM;
  if (this->audio_vpts_rmndr >= AUDIO_SAMPLE_NUM) {
    this->audio_vpts       += 1;
    this->audio_vpts_rmndr -= AUDIO_SAMPLE_NUM;
  }
  this->audio_samples += nsamples;
  this->vpts_offset += nsamples * this->audio_drift_step / AUDIO_SAMPLE_NUM;

  lprintf("audio vpts for %10"PRId64" : %10"PRId64"\n", pts, vpts);

  pthread_mutex_unlock (&this->lock);

  return vpts;
}

static void metronom_set_option (metronom_t *this, int option, int64_t value) {

  pthread_mutex_lock (&this->lock);

  if (this->master) {
    /* pass the option on to the master */
    this->master->set_option(this->master, option, value);
    pthread_mutex_unlock(&this->lock);
    return;
  }

  switch (option) {
  case METRONOM_AV_OFFSET:
    this->av_offset = value;
    xprintf(this->xine, XINE_VERBOSITY_LOG, "av_offset=%" PRId64 " pts\n", this->av_offset);
    break;
  case METRONOM_SPU_OFFSET:
    this->spu_offset = value;
    xprintf(this->xine, XINE_VERBOSITY_LOG, "spu_offset=%" PRId64 " pts\n", this->spu_offset);
    break;
  case METRONOM_ADJ_VPTS_OFFSET:
    this->audio_vpts      += value;
    this->audio_vpts_rmndr = 0;

    /* that message should be rare, please report otherwise.
     * when xine is in some sort of "steady state" hearing it
     * once in a while means a small sound card drift (or system
     * clock drift -- who knows?). nothing to worry about.
     */
    xprintf(this->xine, XINE_VERBOSITY_LOG, "fixing sound card drift by %" PRId64 " pts\n", value);
    break;
  case METRONOM_PREBUFFER:
    this->prebuffer = value;
    xprintf(this->xine, XINE_VERBOSITY_LOG, "prebuffer=%" PRId64 " pts\n", this->prebuffer);
    break;
  default:
    xprintf(this->xine, XINE_VERBOSITY_NONE, "unknown option in set_option: %d\n", option);
  }

  pthread_mutex_unlock (&this->lock);
}

static void metronom_clock_set_option (metronom_clock_t *this,
					int option, int64_t value) {

  pthread_mutex_lock (&this->lock);

  switch (option) {
  case CLOCK_SCR_ADJUSTABLE:
    this->scr_adjustable = value;
    break;
  default:
    xprintf(this->xine, XINE_VERBOSITY_NONE, "unknown option in set_option: %d\n", option);
  }

  pthread_mutex_unlock (&this->lock);
}

static int64_t metronom_get_option (metronom_t *this, int option) {

  if (this->master)
    return this->master->get_option(this->master, option);

  switch (option) {
  case METRONOM_AV_OFFSET:
    return this->av_offset;
  case METRONOM_SPU_OFFSET:
    return this->spu_offset;
  case METRONOM_FRAME_DURATION:
    return this->img_duration;
  case METRONOM_VPTS_OFFSET:
    return this->vpts_offset;
  case METRONOM_PREBUFFER:
    return this->prebuffer;
  }
  xprintf(this->xine, XINE_VERBOSITY_NONE, "unknown option in get_option: %d\n", option);
  return 0;
}

static int64_t metronom_clock_get_option (metronom_clock_t *this, int option) {
  switch (option) {
  case CLOCK_SCR_ADJUSTABLE:
    return this->scr_adjustable;
  }
  xprintf(this->xine, XINE_VERBOSITY_NONE, "unknown option in get_option: %d\n", option);
  return 0;
}

static void metronom_set_master(metronom_t *this, metronom_t *master) {
  metronom_t *old_master = this->master;

  pthread_mutex_lock(&this->lock);
  /* someone might currently be copying values from the old master,
   * so we need his lock too */
  if (old_master) pthread_mutex_lock(&old_master->lock);
  this->master = master;
  /* new master -> we have to reinit */
  this->discontinuity_handled_count = 0;
  if (old_master) pthread_mutex_unlock(&old_master->lock);
  pthread_mutex_unlock(&this->lock);
}

static scr_plugin_t* get_master_scr(metronom_clock_t *this) {
  int select = -1, maxprio = 0, i;

  /* find the SCR provider with the highest priority */
  for (i=0; i<MAX_SCR_PROVIDERS; i++) if (this->scr_list[i]) {
    scr_plugin_t *scr = this->scr_list[i];

    if (maxprio < scr->get_priority(scr)) {
      select = i;
      maxprio = scr->get_priority(scr);
    }
  }
  if (select < 0) {
    xprintf(this->xine, XINE_VERBOSITY_NONE, "panic - no scr provider found!\n");
    return NULL;
  }
  return this->scr_list[select];
}

static int metronom_register_scr (metronom_clock_t *this, scr_plugin_t *scr) {
  int i;

  if (scr->interface_version != 3) {
    xprintf(this->xine, XINE_VERBOSITY_NONE,
            "wrong interface version for scr provider!\n");
    return -1;
  }

  for (i=0; i<MAX_SCR_PROVIDERS; i++)
    if (this->scr_list[i] == NULL) break;
  if (i >= MAX_SCR_PROVIDERS)
    return -1; /* No free slot available */

  scr->clock = this;
  this->scr_list[i] = scr;
  this->scr_master = get_master_scr(this);
  return 0;
}

static void metronom_unregister_scr (metronom_clock_t *this, scr_plugin_t *scr) {
  int i;
  int64_t time;

  /* never unregister scr_list[0]! */
  for (i=1; i<MAX_SCR_PROVIDERS; i++)
    if (this->scr_list[i] == scr)
      break;

  if (i >= MAX_SCR_PROVIDERS)
    return; /* Not found */

  this->scr_list[i] = NULL;
  time = this->get_current_time(this);

  /* master could have been adjusted, others must follow now */
  for (i=0; i<MAX_SCR_PROVIDERS; i++)
    if (this->scr_list[i]) this->scr_list[i]->adjust(this->scr_list[i], time);

  this->scr_master = get_master_scr(this);
}

static int metronom_sync_loop (metronom_clock_t *this) {

  struct timeval tv;
  struct timespec ts;
  scr_plugin_t** scr;
  int64_t        pts;

  while (this->thread_running) {
    /* synchronise every 5 seconds */
    pthread_mutex_lock (&this->lock);

    pts = this->scr_master->get_current(this->scr_master);

    for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
      if (*scr && *scr != this->scr_master) (*scr)->adjust(*scr, pts);

    gettimeofday(&tv, NULL);
    ts.tv_sec  = tv.tv_sec + 5;
    ts.tv_nsec = tv.tv_usec * 1000;
    pthread_cond_timedwait (&this->cancel, &this->lock, &ts);

    pthread_mutex_unlock (&this->lock);
  }
  return 0;
}

static void metronom_exit (metronom_t *this) {

  pthread_mutex_destroy (&this->lock);
  pthread_cond_destroy (&this->video_discontinuity_reached);
  pthread_cond_destroy (&this->audio_discontinuity_reached);

  free (this);
}

static void metronom_clock_exit (metronom_clock_t *this) {

  scr_plugin_t** scr;

  this->thread_running = 0;

  pthread_mutex_lock (&this->lock);
  pthread_cond_signal (&this->cancel);
  pthread_mutex_unlock (&this->lock);

  pthread_join (this->sync_thread, NULL);

  pthread_mutex_destroy (&this->lock);
  pthread_cond_destroy (&this->cancel);

  for (scr = this->scr_list; scr < this->scr_list+MAX_SCR_PROVIDERS; scr++)
    if (*scr) (*scr)->exit(*scr);

  free (this->scr_list);
  free (this);
}


metronom_t * _x_metronom_init (int have_video, int have_audio, xine_t *xine) {

  metronom_t *this = calloc(1, sizeof (metronom_t));

  this->set_audio_rate             = metronom_set_audio_rate;
  this->got_video_frame            = metronom_got_video_frame;
  this->got_audio_samples          = metronom_got_audio_samples;
  this->got_spu_packet             = metronom_got_spu_packet;
  this->handle_audio_discontinuity = metronom_handle_audio_discontinuity;
  this->handle_video_discontinuity = metronom_handle_video_discontinuity;
  this->set_option                 = metronom_set_option;
  this->get_option                 = metronom_get_option;
  this->set_master                 = metronom_set_master;
  this->exit                       = metronom_exit;

  this->xine                       = xine;
  this->master                     = NULL;

  pthread_mutex_init (&this->lock, NULL);

  this->prebuffer                   = PREBUFFER_PTS_OFFSET;
  this->av_offset                   = 0;
  this->spu_offset                  = 0;
  this->vpts_offset                 = 0;

  /* initialize video stuff */

  this->video_vpts                  = this->prebuffer;
  this->video_drift                 = 0;
  this->video_drift_step            = 0;
  this->video_discontinuity_count   = 0;
  this->discontinuity_handled_count = 0;
  pthread_cond_init (&this->video_discontinuity_reached, NULL);
  this->img_duration              = 3000;
  this->img_cpt                   = 0;
  this->last_video_pts            = 0;
  this->last_audio_pts            = 0;


  /* initialize audio stuff */

  this->have_video                  = have_video;
  this->have_audio                  = have_audio;
  this->audio_vpts                  = this->prebuffer;
  this->audio_vpts_rmndr            = 0;
  this->audio_discontinuity_count   = 0;
  pthread_cond_init (&this->audio_discontinuity_reached, NULL);


  return this;
}


metronom_clock_t *_x_metronom_clock_init(xine_t *xine)
{
  metronom_clock_t *this = calloc(1, sizeof(metronom_clock_t));
  int err;

  this->set_option           = metronom_clock_set_option;
  this->get_option           = metronom_clock_get_option;
  this->start_clock          = metronom_start_clock;
  this->stop_clock           = metronom_stop_clock;
  this->resume_clock         = metronom_resume_clock;
  this->get_current_time     = metronom_get_current_time;
  this->adjust_clock         = metronom_adjust_clock;
  this->set_fine_speed       = metronom_set_speed;
  this->register_scr         = metronom_register_scr;
  this->unregister_scr       = metronom_unregister_scr;
  this->exit                 = metronom_clock_exit;

  this->xine                 = xine;
  this->scr_adjustable       = 1;
  this->scr_list             = calloc(MAX_SCR_PROVIDERS, sizeof(void*));
  this->register_scr(this, unixscr_init());

  pthread_mutex_init (&this->lock, NULL);
  pthread_cond_init (&this->cancel, NULL);

  this->thread_running       = 1;

  if ((err = pthread_create(&this->sync_thread, NULL,
			    (void*(*)(void*)) metronom_sync_loop, this)) != 0)
    xprintf(this->xine, XINE_VERBOSITY_NONE, "cannot create sync thread (%s)\n",
	    strerror(err));

  return this;
}