* Implementation of a frame-dropping algorithm for the libmpeg2 plug-in
authorChristophe Massiot <massiot@videolan.org>
Mon, 14 Apr 2003 22:22:32 +0000 (22:22 +0000)
committerChristophe Massiot <massiot@videolan.org>
Mon, 14 Apr 2003 22:22:32 +0000 (22:22 +0000)
  (incomplete).

Makefile.am
include/vlc_common.h
include/vout_synchro.h [new file with mode: 0644]
modules/codec/libmpeg2.c
src/misc/modules.c
src/video_output/video_output.c
src/video_output/vout_synchro.c [new file with mode: 0644]

index 61b6def..494f197 100644 (file)
@@ -203,6 +203,7 @@ HEADERS_include = \
        include/vlc_playlist.h \
        include/vlc_threads.h \
        include/vlc_threads_funcs.h \
+       include/vout_synchro.h \
        include/win32_specific.h \
        include/osd.h \
        $(NULL)
@@ -387,6 +388,7 @@ SOURCES_libvlc_common = \
        src/video_output/video_text.c \
        src/video_output/video_text.h \
        src/video_output/vout_subpictures.c \
+       src/video_output/vout_synchro.c \
        src/audio_output/common.c \
        src/audio_output/dec.c \
        src/audio_output/filters.c \
index 7ae22b1..b304746 100644 (file)
@@ -3,7 +3,7 @@
  * Collection of useful common types and macros definitions
  *****************************************************************************
  * Copyright (C) 1998, 1999, 2000 VideoLAN
- * $Id: vlc_common.h,v 1.60 2003/04/13 20:00:20 fenrir Exp $
+ * $Id: vlc_common.h,v 1.61 2003/04/14 22:22:32 massiot Exp $
  *
  * Authors: Samuel Hocevar <sam@via.ecp.fr>
  *          Vincent Seguin <seguin@via.ecp.fr>
@@ -242,6 +242,7 @@ typedef struct picture_sys_t picture_sys_t;
 typedef struct picture_heap_t picture_heap_t;
 typedef struct subpicture_t subpicture_t;
 typedef struct subpicture_sys_t subpicture_sys_t;
+typedef struct vout_synchro_t vout_synchro_t;
 
 /* Stream output */
 typedef struct sout_instance_t sout_instance_t;
diff --git a/include/vout_synchro.h b/include/vout_synchro.h
new file mode 100644 (file)
index 0000000..d63cb1d
--- /dev/null
@@ -0,0 +1,89 @@
+/*****************************************************************************
+ * vout_synchro.h: frame-dropping structures
+ *****************************************************************************
+ * Copyright (C) 1999-2003 VideoLAN
+ * $Id: vout_synchro.h,v 1.1 2003/04/14 22:22:32 massiot Exp $
+ *
+ * Authors: Christophe Massiot <massiot@via.ecp.fr>
+ *          Jean-Marc Dressler <polux@via.ecp.fr>
+ *          Stéphane Borel <stef@via.ecp.fr>
+ *
+ * This program 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.
+ * 
+ * This program 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * vout_synchro_t : timers for the video synchro
+ *****************************************************************************/
+#define MAX_PIC_AVERAGE         8
+
+/* Read the discussion on top of vout_synchro.c for more information. */
+struct vout_synchro_t
+{
+    VLC_COMMON_MEMBERS
+
+    vout_thread_t * p_vout;
+    int             i_frame_rate;
+    int             i_current_rate;
+
+    /* date of the beginning of the decoding of the current picture */
+    mtime_t         decoding_start;
+
+    /* stream properties */
+    unsigned int    i_n_p, i_n_b;
+
+    /* decoding values */
+    mtime_t         p_tau[4];                  /* average decoding durations */
+    unsigned int    pi_meaningful[4];            /* number of durations read */
+    /* and p_vout->render_time (read with p_vout->change_lock) */
+
+    /* stream context */
+    vlc_bool_t      i_nb_ref;                /* Number of reference pictures */
+    unsigned int    i_eta_p, i_eta_b;
+    mtime_t         backward_pts, current_pts;
+    int             i_current_period;   /* period to add to the next picture */
+    int             i_backward_period;  /* period to add after the next
+                                         * reference picture
+                                         * (backward_period * period / 2) */
+
+    /* statistics */
+    unsigned int    i_trashed_pic, i_not_chosen_pic, i_pic;
+};
+
+/* Pictures types */
+#define I_CODING_TYPE           1
+#define P_CODING_TYPE           2
+#define B_CODING_TYPE           3     
+#define D_CODING_TYPE           4 /* MPEG-1 ONLY */
+/* other values are reserved */
+
+/* Structures */
+#define TOP_FIELD               1
+#define BOTTOM_FIELD            2
+#define FRAME_STRUCTURE         3
+
+/*****************************************************************************
+ * Prototypes
+ *****************************************************************************/
+#define vout_SynchroInit(a,b,c) __vout_SynchroInit(VLC_OBJECT(a),b,c)
+VLC_EXPORT( vout_synchro_t *, __vout_SynchroInit, ( vlc_object_t *, vout_thread_t *, int ) );
+VLC_EXPORT( void, vout_SynchroRelease,        ( vout_synchro_t * ) );
+VLC_EXPORT( void, vout_SynchroReset,          ( vout_synchro_t * ) );
+VLC_EXPORT( vlc_bool_t, vout_SynchroChoose,   ( vout_synchro_t *, int ) );
+VLC_EXPORT( void, vout_SynchroTrash,          ( vout_synchro_t * ) );
+VLC_EXPORT( void, vout_SynchroDecode,         ( vout_synchro_t * ) );
+VLC_EXPORT( void, vout_SynchroEnd,            ( vout_synchro_t *, int, vlc_bool_t ) );
+VLC_EXPORT( mtime_t, vout_SynchroDate,        ( vout_synchro_t * ) );
+VLC_EXPORT( void, vout_SynchroNewPicture,     ( vout_synchro_t *, int, int, mtime_t, mtime_t, int ) );
+
index 2fb63b4..ad08e34 100755 (executable)
@@ -2,7 +2,7 @@
  * libmpeg2.c: mpeg2 video decoder module making use of libmpeg2.
  *****************************************************************************
  * Copyright (C) 1999-2001 VideoLAN
- * $Id: libmpeg2.c,v 1.8 2003/04/07 17:35:01 gbazin Exp $
+ * $Id: libmpeg2.c,v 1.9 2003/04/14 22:22:32 massiot Exp $
  *
  * Authors: Gildas Bazin <gbazin@netcourrier.com>
  *
@@ -34,6 +34,8 @@
 
 #include <mpeg2dec/mpeg2.h>
 
+#include "vout_synchro.h"
+
 /* Aspect ratio (ISO/IEC 13818-2 section 6.3.3, table 6-3) */
 #define AR_SQUARE_PICTURE       1                           /* square pixels */
 #define AR_3_4_PICTURE          2                        /* 3:4 picture (TV) */
@@ -60,11 +62,14 @@ typedef struct dec_thread_t
     mtime_t          i_previous_pts;
     mtime_t          i_current_pts;
     mtime_t          i_period_remainder;
+    int              i_current_rate;
+    picture_t *      p_picture_to_destroy;
 
     /*
      * Output properties
      */
     vout_thread_t *p_vout;
+    vout_synchro_t *p_synchro;
 
 } dec_thread_t;
 
@@ -102,6 +107,7 @@ static int OpenDecoder( vlc_object_t *p_this )
     p_fifo->pf_run = RunDecoder;
     return VLC_SUCCESS;
 }
+
 /*****************************************************************************
  * RunDecoder: the libmpeg2 decoder
  *****************************************************************************/
@@ -132,6 +138,7 @@ static int RunDecoder( decoder_fifo_t *p_fifo )
     p_dec->i_current_pts  = 0;
     p_dec->i_previous_pts = 0;
     p_dec->i_period_remainder = 0;
+    p_dec->p_picture_to_destroy = NULL;
 
     /* Initialize decoder */
     p_dec->p_mpeg2dec = mpeg2_init();
@@ -163,6 +170,14 @@ static int RunDecoder( decoder_fifo_t *p_fifo )
                     break;
                 }
 
+                if( p_dec->p_pes->b_discontinuity )
+                {
+                    vout_SynchroReset( p_dec->p_synchro );
+                    if ( p_dec->p_info->current_fbuf != NULL )
+                        p_dec->p_picture_to_destroy
+                            = p_dec->p_info->current_fbuf->id;
+                }
+
                 if( p_dec->p_pes->i_pts )
                 {
                     mpeg2_pts( p_dec->p_mpeg2dec,
@@ -170,6 +185,8 @@ static int RunDecoder( decoder_fifo_t *p_fifo )
                     p_dec->i_previous_pts = p_dec->i_current_pts;
                     p_dec->i_current_pts = p_dec->p_pes->i_pts;
                 }
+
+                p_dec->i_current_rate = p_dec->p_pes->i_rate;
                 p_data = p_dec->p_pes->p_first;
             }
 
@@ -187,6 +204,7 @@ static int RunDecoder( decoder_fifo_t *p_fifo )
         {
             /* Initialize video output */
             uint8_t *buf[3];
+            buf[0] = buf[1] = buf[2] = NULL;
 
             /* Check whether the input gives a particular aspect ratio */
             if( p_dec->p_fifo->p_demux_data
@@ -231,76 +249,86 @@ static int RunDecoder( decoder_fifo_t *p_fifo )
             mpeg2_custom_fbuf( p_dec->p_mpeg2dec, 1 );
 
             /* Set the first 2 reference frames */
-            if( (p_pic = GetNewPicture( p_dec, buf )) == NULL ) break;
-            mpeg2_set_buf( p_dec->p_mpeg2dec, buf, p_pic );
-            if( (p_pic = GetNewPicture( p_dec, buf )) == NULL ) break;
-            mpeg2_set_buf( p_dec->p_mpeg2dec, buf, p_pic );
+            mpeg2_set_buf( p_dec->p_mpeg2dec, buf, NULL );
+            mpeg2_set_buf( p_dec->p_mpeg2dec, buf, NULL );
+
+            p_dec->p_synchro = vout_SynchroInit( p_dec->p_fifo, p_dec->p_vout,
+                1000000 * 27 / p_dec->p_info->sequence->frame_period * 1001 );
         }
         break;
 
         case STATE_PICTURE:
         {
             uint8_t *buf[3];
-
-            if( (p_pic = GetNewPicture( p_dec, buf )) == NULL ) break;
-            mpeg2_set_buf( p_dec->p_mpeg2dec, buf, p_pic );
-
-            /* Store the date for the picture */
-            if( p_dec->p_info->current_picture->flags & PIC_FLAG_PTS )
+            buf[0] = buf[1] = buf[2] = NULL;
+
+            vout_SynchroNewPicture( p_dec->p_synchro,
+                p_dec->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
+                p_dec->p_info->current_picture->nb_fields,
+                (p_dec->p_info->current_picture->flags & PIC_FLAG_PTS) ?
+                    ( (p_dec->p_info->current_picture->pts ==
+                                (uint32_t)p_dec->i_current_pts) ?
+                              p_dec->i_current_pts : p_dec->i_previous_pts ) : 0,
+                0,
+                p_dec->i_current_rate );
+
+            if ( !vout_SynchroChoose( p_dec->p_synchro,
+                p_dec->p_info->current_picture->flags & PIC_MASK_CODING_TYPE ) )
+            {
+                mpeg2_skip( p_dec->p_mpeg2dec, 1 );
+                vout_SynchroTrash( p_dec->p_synchro );
+                mpeg2_set_buf( p_dec->p_mpeg2dec, buf, NULL );
+            }
+            else
             {
-                p_pic->date = ( p_dec->p_info->current_picture->pts ==
-                                (uint32_t)p_dec->i_current_pts ) ?
-                              p_dec->i_current_pts : p_dec->i_previous_pts;
+                mpeg2_skip( p_dec->p_mpeg2dec, 0 );
+                vout_SynchroDecode( p_dec->p_synchro );
+                if( (p_pic = GetNewPicture( p_dec, buf )) == NULL ) break;
+                mpeg2_set_buf( p_dec->p_mpeg2dec, buf, p_pic );
             }
         }
-        break;
+        /* pass-through */
 
         case STATE_END:
-        case STATE_SLICE:
             if( p_dec->p_info->display_fbuf
                 && p_dec->p_info->display_fbuf->id )
             {
                 p_pic = (picture_t *)p_dec->p_info->display_fbuf->id;
 
-                /* Date the new picture */
-                if( p_dec->p_info->display_picture->flags & PIC_FLAG_PTS )
-                {
-                    p_dec->i_pts = p_pic->date;
-                    p_dec->i_period_remainder = 0;
-                }
-                else
+                if ( p_pic != NULL )
                 {
-                    p_dec->i_pts += ( (p_dec->p_info->sequence->frame_period +
-                                       p_dec->i_period_remainder) / 27 );
-                    p_dec->i_period_remainder =
-                        p_dec->p_info->sequence->frame_period +
-                        p_dec->i_period_remainder -
-                        ( p_dec->p_info->sequence->frame_period +
-                          p_dec->i_period_remainder ) / 27 * 27;
+                    if ( p_dec->p_picture_to_destroy != p_pic )
+                    {
+                        vout_SynchroEnd( p_dec->p_synchro,
+                            p_dec->p_info->display_picture->flags
+                             & PIC_MASK_CODING_TYPE,
+                            0 );
+                        vout_DatePicture( p_dec->p_vout, p_pic,
+                            vout_SynchroDate( p_dec->p_synchro ) );
+                        vout_DisplayPicture( p_dec->p_vout, p_pic );
+                    }
+                    else
+                    {
+                        p_dec->p_picture_to_destroy = NULL;
+                        vout_SynchroEnd( p_dec->p_synchro,
+                            p_dec->p_info->display_picture->flags
+                             & PIC_MASK_CODING_TYPE,
+                            1 );
+                        vout_DestroyPicture( p_dec->p_vout, p_pic );
+                    }
                 }
-                vout_DatePicture( p_dec->p_vout, p_pic, p_dec->i_pts );
-
-                vout_DisplayPicture( p_dec->p_vout, p_pic );
-
-                /* Handle pulldown by adding some delay to the pts of the next
-                 * picture. */
-                if( p_dec->p_info->display_picture->nb_fields > 2 )
+                if( p_dec->p_info->discard_fbuf &&
+                    p_dec->p_info->discard_fbuf->id )
                 {
-                    int i_repeat_fields =
-                        p_dec->p_info->display_picture->nb_fields - 2;
-
-                    p_dec->i_pts += ( (p_dec->p_info->sequence->frame_period +
-                                       p_dec->i_period_remainder)
-                                      / 27 / 2 * i_repeat_fields );
-                    p_dec->i_period_remainder =
-                        p_dec->p_info->sequence->frame_period +
-                        p_dec->i_period_remainder -
-                        ( p_dec->p_info->sequence->frame_period +
-                          p_dec->i_period_remainder ) / 27 / 2 * 27 * 2;
+                    vout_UnlinkPicture( p_dec->p_vout, p_pic );
                 }
             }
             break;
 
+        case STATE_INVALID:
+            msg_Warn( p_dec->p_fifo, "Received STATE_INVALID" );
+            break;
+
         default:
             break;
         }
@@ -357,6 +385,9 @@ static void CloseDecoder( dec_thread_t * p_dec )
             vout_Request( p_dec->p_fifo, p_dec->p_vout, 0, 0, 0, 0 );
         }
 
+        if( p_dec->p_synchro )
+            vout_SynchroRelease( p_dec->p_synchro );
+
         if( p_dec->p_mpeg2dec ) mpeg2_close( p_dec->p_mpeg2dec );
 
         free( p_dec );
@@ -380,6 +411,7 @@ static picture_t *GetNewPicture( dec_thread_t *p_dec, uint8_t **pp_buf )
     }
     if( p_pic == NULL )
         return NULL;
+    vout_LinkPicture( p_dec->p_vout, p_pic );
 
     pp_buf[0] = p_pic->p[0].p_pixels;
     pp_buf[1] = p_pic->p[1].p_pixels;
index b2e6f0a..3ad94a2 100644 (file)
@@ -2,7 +2,7 @@
  * modules.c : Builtin and plugin modules management functions
  *****************************************************************************
  * Copyright (C) 2001 VideoLAN
- * $Id: modules.c,v 1.117 2003/03/25 15:38:14 gbazin Exp $
+ * $Id: modules.c,v 1.118 2003/04/14 22:22:32 massiot Exp $
  *
  * Authors: Samuel Hocevar <sam@zoy.org>
  *          Ethan C. Baldridge <BaldridgeE@cadmus.com>
@@ -81,6 +81,7 @@
 
 #include "video.h"
 #include "video_output.h"
+#include "vout_synchro.h"
 
 #include "audio_output.h"
 #include "aout_internal.h"
index cf4e1d7..d5474ce 100644 (file)
@@ -5,7 +5,7 @@
  * thread, and destroy a previously oppened video output thread.
  *****************************************************************************
  * Copyright (C) 2000-2001 VideoLAN
- * $Id: video_output.c,v 1.217 2003/03/28 17:02:25 gbazin Exp $
+ * $Id: video_output.c,v 1.218 2003/04/14 22:22:32 massiot Exp $
  *
  * Authors: Vincent Seguin <seguin@via.ecp.fr>
  *
@@ -638,7 +638,7 @@ static void RunThread( vout_thread_t *p_vout)
         display_date = 0;
         current_date = mdate();
 
-#ifdef STATS
+#if 0
         p_vout->c_loops++;
         if( !(p_vout->c_loops % VOUT_STATS_NB_LOOPS) )
         {
diff --git a/src/video_output/vout_synchro.c b/src/video_output/vout_synchro.c
new file mode 100644 (file)
index 0000000..1bab5ce
--- /dev/null
@@ -0,0 +1,522 @@
+/*****************************************************************************
+ * vout_synchro.c : frame dropping routines
+ *****************************************************************************
+ * Copyright (C) 1999-2001 VideoLAN
+ * $Id: vout_synchro.c,v 1.1 2003/04/14 22:22:32 massiot Exp $
+ *
+ * Authors: Christophe Massiot <massiot@via.ecp.fr>
+ *          Samuel Hocevar <sam@via.ecp.fr>
+ *          Jean-Marc Dressler <polux@via.ecp.fr>
+ *
+ * This program 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.
+ * 
+ * This program 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*
+ * DISCUSSION : How to Write an efficient Frame-Dropping Algorithm
+ * ==========
+ *
+ * This implementation is based on mathematical and statistical
+ * developments. Older implementations used an enslavement, considering
+ * that if we're late when reading an I picture, we will decode one frame
+ * less. It had a tendancy to derive, and wasn't responsive enough, which
+ * would have caused trouble with the stream control stuff.
+ *
+ * 1. Structure of a picture stream
+ *    =============================
+ * Between 2 I's, we have for instance :
+ *    I   B   P   B   P   B   P   B   P   B   P   B   I
+ *    t0  t1  t2  t3  t4  t5  t6  t7  t8  t9  t10 t11 t12
+ * Please bear in mind that B's and IP's will be inverted when displaying
+ * (decoding order != presentation order). Thus, t1 < t0.
+ *
+ * 2. Definitions
+ *    ===========
+ * t[0..12]     : Presentation timestamps of pictures 0..12.
+ * t            : Current timestamp, at the moment of the decoding.
+ * T            : Picture period, T = 1/frame_rate.
+ * tau[I,P,B]   : Mean time to decode an [I,P,B] picture.
+ * tauYUV       : Mean time to render a picture (given by the video_output).
+ * tau´[I,P,B] = 2 * tau[I,P,B] + tauYUV
+ *              : Mean time + typical difference (estimated to tau/2, that
+ *                needs to be confirmed) + render time.
+ * DELTA        : A given error margin.
+ *
+ * 3. General considerations
+ *    ======================
+ * We define three types of machines :
+ *      14T > tauI : machines capable of decoding all I pictures
+ *      2T > tauP  : machines capable of decoding all P pictures
+ *      T > tauB   : machines capable of decoding all B pictures
+ *
+ * 4. Decoding of an I picture
+ *    ========================
+ * On fast machines, we decode all I's.
+ * Otherwise :
+ * We can decode an I picture if we simply have enough time to decode it 
+ * before displaying :
+ *      t0 - t > tau´I + DELTA
+ *
+ * 5. Decoding of a P picture
+ *    =======================
+ * On fast machines, we decode all P's.
+ * Otherwise :
+ * First criterion : have time to decode it.
+ *      t2 - t > tau´P + DELTA
+ *
+ * Second criterion : it shouldn't prevent us from displaying the forthcoming
+ * I picture, which is more important.
+ *      t12 - t > tau´P + tau´I + DELTA
+ *
+ * 6. Decoding of a B picture
+ *    =======================
+ * On fast machines, we decode all B's. Otherwise :
+ *      t1 - t > tau´B + DELTA
+ * Since the next displayed I or P is already decoded, we don't have to
+ * worry about it.
+ *
+ * I hope you will have a pleasant flight and do not forget your life
+ * jacket.
+ *                                                  --Meuuh (2000-12-29)
+ */
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <stdlib.h>                                                /* free() */
+#include <string.h>                                    /* memcpy(), memset() */
+
+#include <vlc/vlc.h>
+#include <vlc/vout.h>
+
+#include "vout_synchro.h"
+#include "stream_control.h"
+
+/*
+ * Local prototypes
+ */
+
+/* Error margins */
+#define DELTA                   (int)(0.075*CLOCK_FREQ)
+
+#define DEFAULT_NB_P            5
+#define DEFAULT_NB_B            1
+
+/*****************************************************************************
+ * vout_SynchroInit : You know what ?
+ *****************************************************************************/
+vout_synchro_t * __vout_SynchroInit( vlc_object_t * p_object,
+                                   vout_thread_t * p_vout, int i_frame_rate )
+{
+    vout_synchro_t * p_synchro = vlc_object_create( p_object,
+                                                  sizeof(vout_synchro_t) );
+    if ( p_synchro == NULL )
+    {
+        msg_Err( p_object, "out of memory" );
+        return NULL;
+    }
+    vlc_object_attach( p_synchro, p_vout );
+
+    /* We use a fake stream pattern, which is often right. */
+    p_synchro->i_n_p = p_synchro->i_eta_p = DEFAULT_NB_P;
+    p_synchro->i_n_b = p_synchro->i_eta_b = DEFAULT_NB_B;
+    memset( p_synchro->p_tau, 0, 4 * sizeof(mtime_t) );
+    memset( p_synchro->pi_meaningful, 0, 4 * sizeof(unsigned int) );
+    p_synchro->i_nb_ref = 0;
+    p_synchro->current_pts = mdate() + DEFAULT_PTS_DELAY;
+    p_synchro->backward_pts = 0;
+    p_synchro->i_current_period = p_synchro->i_backward_period = 0;
+    p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic = 
+        p_synchro->i_pic = 0;
+
+    p_synchro->i_frame_rate = i_frame_rate;
+    p_synchro->p_vout = p_vout;
+
+    return p_synchro;
+}
+
+/*****************************************************************************
+ * vout_SynchroRelease : You know what ?
+ *****************************************************************************/
+void vout_SynchroRelease( vout_synchro_t * p_synchro )
+{
+    vlc_object_detach( p_synchro );
+    vlc_object_destroy( p_synchro );
+}
+
+/*****************************************************************************
+ * vout_SynchroReset : Reset the reference picture counter
+ *****************************************************************************/
+void vout_SynchroReset( vout_synchro_t * p_synchro )
+{
+    p_synchro->i_nb_ref = 0;
+}
+
+/*****************************************************************************
+ * vout_SynchroChoose : Decide whether we will decode a picture or not
+ *****************************************************************************/
+vlc_bool_t vout_SynchroChoose( vout_synchro_t * p_synchro, int i_coding_type )
+{
+#define TAU_PRIME( coding_type )    (p_synchro->p_tau[(coding_type)] \
+                                    + (p_synchro->p_tau[(coding_type)] >> 1) \
+                                    + tau_yuv)
+#define S (*p_synchro)
+    /* VPAR_SYNCHRO_DEFAULT */
+    mtime_t         now, period, tau_yuv;
+    mtime_t         pts = 0;
+    vlc_bool_t      b_decode = 0;
+
+    now = mdate();
+    period = 1000000 * 1001 / p_synchro->i_frame_rate
+                     * p_synchro->i_current_rate / DEFAULT_RATE;
+
+    vlc_mutex_lock( &p_synchro->p_vout->change_lock );
+    tau_yuv = p_synchro->p_vout->render_time;
+    vlc_mutex_unlock( &p_synchro->p_vout->change_lock );
+
+    switch( i_coding_type )
+    {
+    case I_CODING_TYPE:
+        if( S.backward_pts )
+        {
+            pts = S.backward_pts;
+        }
+        else
+        {
+            /* displaying order : B B P B B I
+             *                      ^       ^
+             *                      |       +- current picture
+             *                      +- current PTS
+             */
+            pts = S.current_pts + period * (S.i_n_b + 2);
+        }
+
+        if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
+                S.p_tau[I_CODING_TYPE] )
+        {
+            b_decode = 1;
+        }
+        else
+        {
+            b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
+        }
+        if( !b_decode )
+        {
+            msg_Warn( p_synchro,
+                      "synchro trashing I ("I64Fd")", pts - now );
+            p_synchro->i_nb_ref = 0;
+        }
+        else if( p_synchro->i_nb_ref < 2 )
+            p_synchro->i_nb_ref++;
+        break;
+
+    case P_CODING_TYPE:
+        if( S.backward_pts )
+        {
+            pts = S.backward_pts;
+        }
+        else
+        {
+            pts = S.current_pts + period * (S.i_n_b + 1);
+        }
+
+        if( p_synchro->i_nb_ref < 1 )
+        {
+            b_decode = 0;
+        }
+        else if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
+                S.p_tau[I_CODING_TYPE] )
+        {
+            if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
+            {
+                /* Security in case we're _really_ late */
+                b_decode = (pts - now > 0);
+            }
+            else
+            {
+                b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
+                /* next I */
+                b_decode &= (pts - now
+                              + period
+                          * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
+                            > (TAU_PRIME(P_CODING_TYPE)
+                                + TAU_PRIME(I_CODING_TYPE) + DELTA);
+            }
+        }
+        else
+        {
+            b_decode = 0;
+        }
+        if( b_decode )
+            p_synchro->i_nb_ref = 2;
+        else
+            p_synchro->i_nb_ref = 0;
+        break;
+
+    case B_CODING_TYPE:
+        pts = S.current_pts;
+
+        if( p_synchro->i_nb_ref < 2 )
+        {
+            b_decode = 0;
+        }
+        else if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
+        {
+            b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
+        }
+        else
+        {
+            b_decode = 0;
+        }
+    }
+
+    if( !b_decode )
+    {
+        S.i_not_chosen_pic++;
+    }
+    return( b_decode );
+#undef S
+#undef TAU_PRIME
+}
+
+/*****************************************************************************
+ * vout_SynchroTrash : Update counters when we trash a picture
+ *****************************************************************************/
+void vout_SynchroTrash( vout_synchro_t * p_synchro )
+{
+    p_synchro->i_trashed_pic++;
+}
+
+/*****************************************************************************
+ * vout_SynchroDecode : Update timers when we decide to decode a picture
+ *****************************************************************************/
+void vout_SynchroDecode( vout_synchro_t * p_synchro )
+{
+    p_synchro->decoding_start = mdate();
+}
+
+/*****************************************************************************
+ * vout_SynchroEnd : Called when the image is totally decoded
+ *****************************************************************************/
+void vout_SynchroEnd( vout_synchro_t * p_synchro, int i_coding_type,
+                      vlc_bool_t b_garbage )
+{
+    mtime_t     tau;
+
+    if( !b_garbage )
+    {
+        tau = mdate() - p_synchro->decoding_start;
+
+        /* If duration too high, something happened (pause ?), so don't
+         * take it into account. */
+        if( tau < 3 * p_synchro->p_tau[i_coding_type]
+             || !p_synchro->pi_meaningful[i_coding_type] )
+        {
+            /* Mean with average tau, to ensure stability. */
+            p_synchro->p_tau[i_coding_type] =
+                (p_synchro->pi_meaningful[i_coding_type]
+                 * p_synchro->p_tau[i_coding_type] + tau)
+                / (p_synchro->pi_meaningful[i_coding_type] + 1);
+            if( p_synchro->pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
+            {
+                p_synchro->pi_meaningful[i_coding_type]++;
+            }
+        }
+    }
+}
+
+/*****************************************************************************
+ * vout_SynchroDate : When an image has been decoded, ask for its date
+ *****************************************************************************/
+mtime_t vout_SynchroDate( vout_synchro_t * p_synchro )
+{
+    /* No need to lock, since PTS are only used by the video parser. */
+    return p_synchro->current_pts;
+}
+
+/*****************************************************************************
+ * vout_SynchroNewPicture: Update stream structure and PTS
+ *****************************************************************************/
+void vout_SynchroNewPicture( vout_synchro_t * p_synchro, int i_coding_type,
+                             int i_repeat_field, mtime_t next_pts,
+                             mtime_t next_dts, int i_current_rate )
+{
+    mtime_t         period = 1000000 * 1001 / p_synchro->i_frame_rate
+                              * i_current_rate / DEFAULT_RATE;
+#if 0
+    mtime_t         now = mdate(); 
+#endif
+    p_synchro->i_current_rate = i_current_rate;
+
+    switch( i_coding_type )
+    {
+    case I_CODING_TYPE:
+        if( p_synchro->i_eta_p
+             && p_synchro->i_eta_p != p_synchro->i_n_p )
+        {
+#if 0
+            msg_Dbg( p_synchro,
+                     "stream periodicity changed from P[%d] to P[%d]",
+                     p_synchro->i_n_p, p_synchro->i_eta_p );
+#endif
+            p_synchro->i_n_p = p_synchro->i_eta_p;
+        }
+        p_synchro->i_eta_p = p_synchro->i_eta_b = 0;
+
+#if 0
+        msg_Dbg( p_synchro, "I("I64Fd") P("I64Fd")[%d] B("I64Fd")"
+              "[%d] YUV("I64Fd") : trashed %d:%d/%d",
+              p_synchro->p_tau[I_CODING_TYPE],
+              p_synchro->p_tau[P_CODING_TYPE],
+              p_synchro->i_n_p,
+              p_synchro->p_tau[B_CODING_TYPE],
+              p_synchro->i_n_b,
+              p_synchro->p_vout->render_time,
+              p_synchro->i_not_chosen_pic,
+              p_synchro->i_trashed_pic -
+              p_synchro->i_not_chosen_pic,
+              p_synchro->i_pic );
+        p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic
+            = p_synchro->i_pic = 0;
+#else
+        if ( p_synchro->i_pic >= 100 )
+        {
+            msg_Dbg( p_synchro, "decoded %d/%d pictures",
+                     p_synchro->i_pic
+                       - p_synchro->i_trashed_pic,
+                     p_synchro->i_pic );
+            p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic
+                = p_synchro->i_pic = 0;
+        }
+#endif
+        break;
+
+    case P_CODING_TYPE:
+        p_synchro->i_eta_p++;
+        if( p_synchro->i_eta_b
+             && p_synchro->i_eta_b != p_synchro->i_n_b )
+        {
+            msg_Warn( p_synchro,
+                      "stream periodicity changed from B[%d] to B[%d]",
+                      p_synchro->i_n_b, p_synchro->i_eta_b );
+            p_synchro->i_n_b = p_synchro->i_eta_b;
+        }
+        p_synchro->i_eta_b = 0;
+        break;
+    case B_CODING_TYPE:
+        p_synchro->i_eta_b++;
+        break;
+    }
+
+    p_synchro->current_pts += p_synchro->i_current_period
+                                        * (period >> 1);
+#define PTS_THRESHOLD   (period >> 2)
+    if( i_coding_type == B_CODING_TYPE )
+    {
+        /* A video frame can be displayed 1, 2 or 3 times, according to
+         * repeat_first_field, top_field_first, progressive_sequence and
+         * progressive_frame. */
+        p_synchro->i_current_period = i_repeat_field;
+
+        if( next_pts )
+        {
+            if( next_pts - p_synchro->current_pts
+                    > PTS_THRESHOLD
+                 || p_synchro->current_pts - next_pts
+                    > PTS_THRESHOLD )
+            {
+                msg_Warn( p_synchro, "vout synchro warning: pts != "
+                          "current_date ("I64Fd")",
+                          p_synchro->current_pts
+                              - next_pts );
+            }
+            p_synchro->current_pts = next_pts;
+        }
+    }
+    else
+    {
+        p_synchro->i_current_period = p_synchro->i_backward_period;
+        p_synchro->i_backward_period = i_repeat_field;
+
+        if( p_synchro->backward_pts )
+        {
+            if( next_dts && 
+                (next_dts - p_synchro->backward_pts
+                    > PTS_THRESHOLD
+              || p_synchro->backward_pts - next_dts
+                    > PTS_THRESHOLD) )
+            {
+                msg_Warn( p_synchro, "backward_pts != dts ("I64Fd")",
+                           next_dts
+                               - p_synchro->backward_pts );
+            }
+            if( p_synchro->backward_pts - p_synchro->current_pts
+                    > PTS_THRESHOLD
+                 || p_synchro->current_pts - p_synchro->backward_pts
+                    > PTS_THRESHOLD )
+            {
+                msg_Warn( p_synchro,
+                          "backward_pts != current_pts ("I64Fd")",
+                          p_synchro->current_pts
+                              - p_synchro->backward_pts );
+            }
+            p_synchro->current_pts = p_synchro->backward_pts;
+            p_synchro->backward_pts = 0;
+        }
+        else if( next_dts )
+        {
+            if( next_dts - p_synchro->current_pts
+                    > PTS_THRESHOLD
+                 || p_synchro->current_pts - next_dts
+                    > PTS_THRESHOLD )
+            {
+                msg_Warn( p_synchro, "dts != current_pts ("I64Fd")",
+                          p_synchro->current_pts
+                              - next_dts );
+            }
+            /* By definition of a DTS. */
+            p_synchro->current_pts = next_dts;
+            next_dts = 0;
+        }
+
+        if( next_pts )
+        {
+            /* Store the PTS for the next time we have to date an I picture. */
+            p_synchro->backward_pts = next_pts;
+            next_pts = 0;
+        }
+    }
+#undef PTS_THRESHOLD
+
+#if 0
+    /* Removed for incompatibility with slow motion */
+    if( p_synchro->current_pts + DEFAULT_PTS_DELAY < now )
+    {
+        /* We cannot be _that_ late, something must have happened, reinit
+         * the dates. */
+        msg_Warn( p_synchro, "PTS << now ("I64Fd"), resetting",
+                   now - p_synchro->current_pts - DEFAULT_PTS_DELAY );
+        p_synchro->current_pts = now + DEFAULT_PTS_DELAY;
+    }
+    if( p_synchro->backward_pts
+         && p_synchro->backward_pts + DEFAULT_PTS_DELAY < now )
+    {
+        /* The same. */
+        p_synchro->backward_pts = 0;
+    }
+#endif
+
+    p_synchro->i_pic++;
+}