From 1c2a8c7f14a5030367b7f7287667e380935cb706 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Wed, 24 Apr 2002 01:24:06 +0000
Subject: [PATCH] avcodec_flush_buffers()

Originally committed as revision 420 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/avcodec.h   |  6 ++++--
 libavcodec/h263.c      |  4 ++--
 libavcodec/h263dec.c   | 15 +++++++++++----
 libavcodec/mpegvideo.c |  2 ++
 libavcodec/mpegvideo.h |  1 +
 libavcodec/utils.c     |  9 +++++++++
 6 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 26e1b19abf..8cb62ce706 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -5,8 +5,8 @@
 
 #define LIBAVCODEC_VERSION_INT 0x000406
 #define LIBAVCODEC_VERSION     "0.4.6"
-#define LIBAVCODEC_BUILD       4602
-#define LIBAVCODEC_BUILD_STR   "4602"
+#define LIBAVCODEC_BUILD       4603
+#define LIBAVCODEC_BUILD_STR   "4603"
 
 enum CodecID {
     CODEC_ID_NONE, 
@@ -340,6 +340,8 @@ int avcodec_close(AVCodecContext *avctx);
 
 void avcodec_register_all(void);
 
+void avcodec_flush_buffers(AVCodecContext *avctx);
+
 #ifdef FF_POSTPROCESS
 #ifndef MBC
 #define MBC 128
diff --git a/libavcodec/h263.c b/libavcodec/h263.c
index 2694f96808..b7619a3e19 100644
--- a/libavcodec/h263.c
+++ b/libavcodec/h263.c
@@ -1034,7 +1034,7 @@ static void mpeg4_encode_vol_header(MpegEncContext * s)
 
     if(s->low_delay){
         put_bits(&s->pb, 1, 1);		/* vol control parameters= yes */
-        put_bits(&s->pb, 2, 1);		/* chroma format 422 */
+        put_bits(&s->pb, 2, 1);		/* chroma format YUV 420/YV12 */
         put_bits(&s->pb, 1, s->low_delay);
         put_bits(&s->pb, 1, 0);		/* vbv parameters= no */
     }else{
@@ -2602,7 +2602,7 @@ int mpeg4_decode_picture_header(MpegEncContext * s)
         } else {
             vo_ver_id = 1;
         }
-        
+//printf("vo type:%d\n",s->vo_type);
         s->aspect_ratio_info= get_bits(&s->gb, 4);
 	if(s->aspect_ratio_info == EXTENDET_PAR){
             skip_bits(&s->gb, 8); //par_width
diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 9b8606d5e7..7c450f9edd 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -135,7 +135,6 @@ static int h263_decode_frame(AVCodecContext *avctx,
     } else {
         ret = h263_decode_picture_header(s);
     }
-    if(ret==FRAME_SKIPED) return 0;
 
         /* After H263 & mpeg4 header decode we have the height, width,*/
         /* and other parameters. So then we could init the picture   */
@@ -154,9 +153,12 @@ static int h263_decode_frame(AVCodecContext *avctx,
             return -1;
     }
 
+    if(ret==FRAME_SKIPED) return 0;
     if (ret < 0)
         return -1;
-
+    /* skip b frames if we dont have reference frames */
+    if(s->num_available_buffers<2 && s->pict_type==B_TYPE) return 0;
+        
     MPV_frame_start(s);
 
 #ifdef DEBUG
@@ -222,7 +224,8 @@ static int h263_decode_frame(AVCodecContext *avctx,
             }
             MPV_decode_mb(s, s->block);
         }
-        if (avctx->draw_horiz_band) {
+        if (    avctx->draw_horiz_band 
+            && (s->num_available_buffers>=1 || (!s->has_b_frames)) ) {
             UINT8 *src_ptr[3];
             int y, h, offset;
             y = s->mb_y * 16;
@@ -279,7 +282,11 @@ static int h263_decode_frame(AVCodecContext *avctx,
     /* we substract 1 because it is added on utils.c    */
     avctx->frame_number = s->picture_number - 1;
 
-    *data_size = sizeof(AVPicture);
+    /* dont output the last pic after seeking 
+       note we allready added +1 for the current pix in MPV_frame_end(s) */
+    if(s->num_available_buffers>=2 || (!s->has_b_frames))
+        *data_size = sizeof(AVPicture);
+
     return buf_size;
 }
 
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index c1a2cf746a..7eaa18111c 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -629,6 +629,8 @@ void MPV_frame_end(MpegEncContext *s)
         s->last_non_b_pict_type= s->pict_type;
         s->last_non_b_qscale= s->qscale;
         s->last_non_b_mc_mb_var= s->mc_mb_var;
+        s->num_available_buffers++;
+        if(s->num_available_buffers>2) s->num_available_buffers= 2;
     }
 }
 
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 6b67823342..69b9fb8d0e 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -129,6 +129,7 @@ typedef struct MpegEncContext {
     UINT8 *aux_picture[3];       /* aux picture (for B frames only) */
     UINT8 *aux_picture_base[3];  /* real start of the picture */
     UINT8 *current_picture[3];   /* buffer to store the decompressed current picture */
+    int num_available_buffers;   /* is 0 at the start & after seeking, after the first I frame its 1 after next I/P 2 */
     int last_dc[3];              /* last DC values for MPEG1 */
     INT16 *dc_val[3];            /* used for mpeg4 DC prediction, all 3 arrays must be continuous */
     int y_dc_scale, c_dc_scale;
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 7240f2096a..c15b5674ce 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -22,6 +22,7 @@
 #include "common.h"
 #include "dsputil.h"
 #include "avcodec.h"
+#include "mpegvideo.h"
 #ifdef HAVE_MALLOC_H
 #include <malloc.h>
 #else
@@ -479,6 +480,14 @@ PCM_CODEC(CODEC_ID_PCM_MULAW, pcm_mulaw);
 #undef PCM_CODEC
 }
 
+/* this should be called after seeking and before trying to decode the next frame */
+void avcodec_flush_buffers(AVCodecContext *avctx)
+{
+    MpegEncContext *s = avctx->priv_data;
+    s->num_available_buffers=0;
+}
+
+
 static int encode_init(AVCodecContext *s)
 {
     return 0;