timestamps generation improvement when parsing avi

patch by Joakim \ elupus chez ecce dot se /
original thread:
date: 03/19/2007 01:47 AM
subject: [Ffmpeg-devel] [RFC] Improvement for the odd timestamp generation when parser is in use.

Originally committed as revision 8725 to svn://svn.ffmpeg.org/ffmpeg/trunk

3 files changed, 17 insertions, 5 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index c5d5df0197..d6525954bb 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -25,8 +25,8 @@
 extern "C" {
 #endif
 
-#define LIBAVFORMAT_VERSION_INT ((51<<16)+(12<<8)+0)
-#define LIBAVFORMAT_VERSION     51.12.0
+#define LIBAVFORMAT_VERSION_INT ((51<<16)+(12<<8)+1)
+#define LIBAVFORMAT_VERSION     51.12.1
 #define LIBAVFORMAT_BUILD       LIBAVFORMAT_VERSION_INT
 
 #define LIBAVFORMAT_IDENT       "Lavf" AV_STRINGIFY(LIBAVFORMAT_VERSION)
@@ -309,7 +309,8 @@ typedef struct AVStream {
     char language[4]; /** ISO 639 3-letter language code (empty string if undefined) */
 
     /* av_read_frame() support */
-    int need_parsing;                  ///< 1->full parsing needed, 2->only parse headers dont repack
+#define AVSTREAM_PARSE_TIMESTAMPS 3    /**< full parsing and interpolation of timestamps for frames not starting on packet boundary */
+    int need_parsing;                  ///< 1->full parsing needed, 2->only parse headers dont repack, 3->full parsing and interpolate timestamps
     struct AVCodecParserContext *parser;
 
     int64_t cur_dts;
diff --git a/libavformat/avidec.c b/libavformat/avidec.c
index 02078bc77b..d434c57181 100644
--- a/libavformat/avidec.c
+++ b/libavformat/avidec.c
@@ -452,8 +452,8 @@ static int avi_read_header(AVFormatContext *s, AVFormatParameters *ap)
                     if (size%2) /* 2-aligned (fix for Stargate SG-1 - 3x18 - Shades of Grey.avi) */
                         url_fskip(pb, 1);
                     /* Force parsing as several audio frames can be in
-                     * one packet. */
-                    st->need_parsing = 1;
+                     * one packet and timestamps refer to packet start*/
+                    st->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;
                     /* ADTS header is in extradata, AAC without header must be stored as exact frames, parser not needed and it will fail */
                     if (st->codec->codec_id == CODEC_ID_AAC && st->codec->extradata_size)
                         st->need_parsing = 0;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index c82d7dac84..b748b546ca 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -584,6 +584,7 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
                                AVCodecParserContext *pc, AVPacket *pkt)
 {
     int num, den, presentation_delayed, delay, i;
+    int64_t offset;
     /* handle wrapping */
     if(st->cur_dts != AV_NOPTS_VALUE){
         if(pkt->pts != AV_NOPTS_VALUE)
@@ -599,6 +600,16 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
         }
     }
 
+    /* correct timestamps with byte offset if demuxers only have timestamps on packet boundaries */
+    if(pc && st->need_parsing == AVSTREAM_PARSE_TIMESTAMPS && pkt->size){
+        /* this will estimate bitrate based on this frame's duration and size */
+        offset = av_rescale(pc->offset, pkt->duration, pkt->size);
+        if(pkt->pts != AV_NOPTS_VALUE)
+            pkt->pts += offset;
+        if(pkt->dts != AV_NOPTS_VALUE)
+            pkt->dts += offset;
+    }
+
     if(is_intra_only(st->codec))
         pkt->flags |= PKT_FLAG_KEY;