add option to set mpeg1/2 gop timecode start, and drop frame flag timecode flag

Originally committed as revision 6933 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 16 insertions, 4 deletions

diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index ea4108fe16..a7d8dc1dcd 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -240,6 +240,11 @@ static int encode_init(AVCodecContext *avctx)
     if(avctx->level == FF_LEVEL_UNKNOWN)
         avctx->level = s->chroma_format == CHROMA_420 ? 8 : 5;
 
+    if((avctx->flags2 & CODEC_FLAG2_DROP_FRAME_TIMECODE) && s->frame_rate_index != 4){
+        av_log(avctx, AV_LOG_ERROR, "Drop frame time code only allowed with 1001/30000 fps\n");
+        return -1;
+    }
+
     return 0;
 }
 
@@ -346,13 +351,20 @@ static void mpeg1_encode_sequence_header(MpegEncContext *s)
             }
 
             put_header(s, GOP_START_CODE);
-            put_bits(&s->pb, 1, 0); /* do drop frame */
+            put_bits(&s->pb, 1, !!(s->avctx->flags & CODEC_FLAG2_DROP_FRAME_TIMECODE)); /* drop frame flag */
             /* time code : we must convert from the real frame rate to a
                fake mpeg frame rate in case of low frame rate */
             fps = (framerate.num + framerate.den/2)/ framerate.den;
-            time_code = s->current_picture_ptr->coded_picture_number;
-
-            s->gop_picture_number = time_code;
+            time_code = s->current_picture_ptr->coded_picture_number + s->avctx->timecode_frame_start;
+
+            s->gop_picture_number = s->current_picture_ptr->coded_picture_number;
+            if (s->avctx->flags2 & CODEC_FLAG2_DROP_FRAME_TIMECODE) {
+                /* only works for NTSC 29.97 */
+                int d = time_code / 17982;
+                int m = time_code % 17982;
+                //if (m < 2) m += 2; /* not needed since -2,-1 / 2 in C returns 0 */
+                time_code += 18 * d + 2 * ((m - 2) / 1798);
+            }
             put_bits(&s->pb, 5, (uint32_t)((time_code / (fps * 3600)) % 24));
             put_bits(&s->pb, 6, (uint32_t)((time_code / (fps * 60)) % 60));
             put_bits(&s->pb, 1, 1);