X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fmpeg12.c;h=56b456a0783b5e8a00fb2db3892283bc36ab77a4;hb=31304587da246672a240216d95298bb0ba9f9c64;hp=87f673d121312a41449e84032799090da71a6d9e;hpb=e68c7a4abe9c259af44e3cc1414674743e76cc32;p=ffmpeg

diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 87f673d1213..56b456a0783 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -1869,7 +1869,7 @@ static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,
         }
     }
 eos: // end of slice
-    *buf += get_bits_count(&s->gb)/8 - 1;
+    *buf += (get_bits_count(&s->gb)-1)/8;
 //printf("y %d %d %d %d\n", s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y);
     return 0;
 }
@@ -2182,29 +2182,43 @@ int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
     int i;
     uint32_t state= pc->state;
 
-    i=0;
-    if(!pc->frame_start_found){
-        for(i=0; i<buf_size; i++){
+    /* EOF considered as end of frame */
+    if (buf_size == 0)
+        return 0;
+
+/*
+ 0  frame start         -> 1/4
+ 1  first_SEQEXT        -> 0/2
+ 2  first field start   -> 3/0
+ 3  second_SEQEXT       -> 2/0
+ 4  searching end
+*/
+
+    for(i=0; i<buf_size; i++){
+        assert(pc->frame_start_found>=0 && pc->frame_start_found<=4);
+        if(pc->frame_start_found&1){
+            if(state == EXT_START_CODE && (buf[i]&0xF0) != 0x80)
+                pc->frame_start_found--;
+            else if(state == EXT_START_CODE+2){
+                if((buf[i]&3) == 3) pc->frame_start_found= 0;
+                else                pc->frame_start_found= (pc->frame_start_found+1)&3;
+            }
+            state++;
+        }else{
             i= ff_find_start_code(buf+i, buf+buf_size, &state) - buf - 1;
-            if(state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE){
+            if(pc->frame_start_found==0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE){
                 i++;
-                pc->frame_start_found=1;
-                break;
+                pc->frame_start_found=4;
             }
             if(state == SEQ_END_CODE){
                 pc->state=-1;
                 return i+1;
             }
-        }
-    }
-
-    if(pc->frame_start_found){
-        /* EOF considered as end of frame */
-        if (buf_size == 0)
-            return 0;
-        for(; i<buf_size; i++){
-            i= ff_find_start_code(buf+i, buf+buf_size, &state) - buf - 1;
-            if((state&0xFFFFFF00) == 0x100){
+            if(pc->frame_start_found==2 && state == SEQ_START_CODE)
+                pc->frame_start_found= 0;
+            if(pc->frame_start_found<4 && state == EXT_START_CODE)
+                pc->frame_start_found++;
+            if(pc->frame_start_found == 4 && (state&0xFFFFFF00) == 0x100){
                 if(state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE){
                     pc->frame_start_found=0;
                     pc->state=-1;