lavf/dv: do not set video timebase more than once

Current code will call avpriv_set_pts_info() for each video frame,
possibly setting a different timebase if the stream framerate changes.
This violates API conventions, as the timebase is supposed to stay
constant after stream creation.

Change the demuxer to set a single timebase that is fine enough to
handle all supported DV framerates.

The seek tests change slightly because the new timebase is more
granular.

1 files changed, 27 insertions, 9 deletions

diff --git a/libavformat/dv.c b/libavformat/dv.c
index ffed1a7a90..9888c10b48 100644
--- a/libavformat/dv.c
+++ b/libavformat/dv.c
@@ -69,6 +69,8 @@ struct DVDemuxContext {
     uint8_t           audio_buf[4][8192];
     int               ach;
     int               frames;
+
+    int64_t           next_pts_video;
 };
 
 static inline uint16_t dv_audio_12to16(uint16_t sample)
@@ -314,8 +316,6 @@ static int dv_extract_video_info(DVDemuxContext *c, const uint8_t *frame)
 
     par = c->vst->codecpar;
 
-    avpriv_set_pts_info(c->vst, 64, c->sys->time_base.num,
-                        c->sys->time_base.den);
     c->vst->avg_frame_rate = av_inv_q(c->vst->time_base);
 
     /* finding out SAR is a little bit messy */
@@ -360,6 +360,8 @@ static int dv_init_demux(AVFormatContext *s, DVDemuxContext *c)
     c->vst->codecpar->bit_rate   = 25000000;
     c->vst->start_time        = 0;
 
+    avpriv_set_pts_info(c->vst, 64, 1, DV_TIMESCALE_VIDEO);
+
     /* Audio streams are added later as they are encountered. */
     s->ctx_flags |= AVFMTCTX_NOHEADER;
 
@@ -463,7 +465,10 @@ int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
         pkt->size         = size;
         pkt->flags       |= AV_PKT_FLAG_KEY;
         pkt->stream_index = c->vst->index;
-        pkt->pts          = c->frames;
+        pkt->pts          = c->next_pts_video;
+        pkt->duration     = av_rescale_q(1, c->sys->time_base, c->vst->time_base);
+
+        c->next_pts_video += pkt->duration;
     }
 
     c->frames++;
@@ -472,28 +477,34 @@ int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
 }
 
 static int64_t dv_frame_offset(AVFormatContext *s, DVDemuxContext *c,
-                               int64_t timestamp, int flags)
+                               int64_t *timestamp)
 {
     // FIXME: sys may be wrong if last dv_read_packet() failed (buffer is junk)
     FFFormatContext *const si = ffformatcontext(s);
     const int frame_size = c->sys->frame_size;
+    int64_t  frame_count = av_rescale_q(*timestamp, c->vst->time_base, c->sys->time_base);
     int64_t offset;
     int64_t size       = avio_size(s->pb) - si->data_offset;
     int64_t max_offset = ((size - 1) / frame_size) * frame_size;
 
-    offset = frame_size * timestamp;
+    offset = frame_size * frame_count;
 
     if (size >= 0 && offset > max_offset)
         offset = max_offset;
     else if (offset < 0)
         offset = 0;
 
+    *timestamp = av_rescale_q(offset / frame_size, c->sys->time_base, c->vst->time_base);
+
     return offset + si->data_offset;
 }
 
-void ff_dv_offset_reset(DVDemuxContext *c, int64_t frame_offset)
+void ff_dv_ts_reset(DVDemuxContext *c, int64_t ts)
 {
-    c->frames = frame_offset;
+    c->frames         = !c->sys ? 0 :
+                        av_rescale_q(ts, c->vst->time_base, c->sys->time_base);
+    c->next_pts_video = ts;
+
     c->audio_pkt[0].size = c->audio_pkt[1].size = 0;
     c->audio_pkt[2].size = c->audio_pkt[3].size = 0;
 }
@@ -618,12 +629,19 @@ static int dv_read_seek(AVFormatContext *s, int stream_index,
 {
     RawDVContext *r   = s->priv_data;
     DVDemuxContext *c = &r->dv_demux;
-    int64_t offset    = dv_frame_offset(s, c, timestamp, flags);
+    int64_t offset;
+
+    // seek using the video stream
+    if (stream_index != c->vst->index)
+        timestamp = av_rescale_q(timestamp, s->streams[stream_index]->time_base,
+                                 c->vst->time_base);
+
+    offset = dv_frame_offset(s, c, &timestamp);
 
     if (avio_seek(s->pb, offset, SEEK_SET) < 0)
         return -1;
 
-    ff_dv_offset_reset(c, offset / c->sys->frame_size);
+    ff_dv_ts_reset(c, timestamp);
     return 0;
 }