mpegvideo: don't pretend the first frame is always a key frame

Signed-off-by: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>

Modify the parser initialization so that parsers can
set pict_type themselves.  Use this in the mpegvideo parser
so that initial frames are not unconditionally I frames.
I have had this in my tree for several years.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpegvideo_parser.c

@@ -182,9 +182,16 @@ static int mpegvideo_split(AVCodecContext *avctx,
     return 0;
 }
 
+static int mpegvideo_parse_init(AVCodecParserContext *s)
+{
+    s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial
+    return 0;
+}
+
 AVCodecParser ff_mpegvideo_parser = {
     .codec_ids      = { CODEC_ID_MPEG1VIDEO, CODEC_ID_MPEG2VIDEO },
     .priv_data_size = sizeof(struct MpvParseContext),
+    .parser_init    = mpegvideo_parse_init,
     .parser_parse   = mpegvideo_parse,
     .parser_close   = ff_parse_close,
     .split          = mpegvideo_split,

libavcodec/parser.c

@@ -63,6 +63,8 @@ AVCodecParserContext *av_parser_init(int codec_id)
         av_free(s);
         return NULL;
     }
+    s->fetch_timestamp=1;
+    s->pict_type = AV_PICTURE_TYPE_I;
     if (parser->parser_init) {
         ret = parser->parser_init(s);
         if (ret != 0) {
@@ -71,8 +73,6 @@ AVCodecParserContext *av_parser_init(int codec_id)
             return NULL;
         }
     }
-    s->fetch_timestamp=1;
-    s->pict_type = AV_PICTURE_TYPE_I;
     s->key_frame = -1;
     s->convergence_duration = 0;
     s->dts_sync_point       = INT_MIN;

tests/ref/seek/lavf_mpg

@@ -16,7 +16,7 @@ ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st:-1 flags:1  ts:-0.740831
 ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st: 0 flags:0  ts: 2.153333
-ret: 0         st: 0 flags:1 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
+ret: 0         st: 0 flags:0 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
 ret: 0         st: 0 flags:1  ts: 1.047500
 ret: 0         st: 0 flags:0 dts: 1.040000 pts: 1.080000 pos:  40960 size: 16073
 ret: 0         st: 1 flags:0  ts:-0.058333
@@ -30,7 +30,7 @@ ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st: 0 flags:0  ts:-0.481667
 ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st: 0 flags:1  ts: 2.412500
-ret: 0         st: 0 flags:1 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
+ret: 0         st: 0 flags:0 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
 ret: 0         st: 1 flags:0  ts: 1.306667
 ret: 0         st: 1 flags:1 dts: 1.522444 pts: 1.522444 pos: 342028 size:   314
 ret: 0         st: 1 flags:1  ts: 0.200844
@@ -38,7 +38,7 @@ ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st:-1 flags:0  ts:-0.904994
 ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st:-1 flags:1  ts: 1.989173
-ret: 0         st: 0 flags:1 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
+ret: 0         st: 0 flags:0 dts: 1.920000 pts: 1.960000 pos: 339968 size:   681
 ret: 0         st: 0 flags:0  ts: 0.883344
 ret: 0         st: 1 flags:1 dts: 1.000000 pts: 1.000000 pos:   2048 size:   208
 ret: 0         st: 0 flags:1  ts:-0.222489