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Diffstat (limited to 'libmpdemux/demux_mpg.c')
-rw-r--r--libmpdemux/demux_mpg.c168
1 files changed, 122 insertions, 46 deletions
diff --git a/libmpdemux/demux_mpg.c b/libmpdemux/demux_mpg.c
index af888b4764..0bd53d8ce9 100644
--- a/libmpdemux/demux_mpg.c
+++ b/libmpdemux/demux_mpg.c
@@ -29,8 +29,10 @@
typedef struct mpg_demuxer {
float last_pts;
- float final_pts;
- int has_valid_timestamps;
+ float first_pts; // first pts found in stream
+ float first_to_final_pts_len; // difference between final pts and first pts
+ int has_valid_timestamps; // !=0 iff time stamps look linear
+ // (not necessarily starting with 0)
unsigned int es_map[0x40]; //es map of stream types (associated to the pes id) from 0xb0 to 0xef
int num_a_streams;
int a_stream_ids[MAX_A_STREAMS];
@@ -102,49 +104,123 @@ static int parse_psm(demuxer_t *demux, int len) {
// 500000 is a wild guess
#define TIMESTAMP_PROBE_LEN 500000
+//MAX_PTS_DIFF_FOR_CONSECUTIVE denotes the maximum difference
+//between two pts to consider them consecutive
+//1.0 is a wild guess
+#define MAX_PTS_DIFF_FOR_CONSECUTIVE 1.0
+
+//returns the first pts found within TIME_STAMP_PROBE_LEN bytes after stream_pos in demuxer's stream.
+//if no pts is found or an error occurs, -1.0 is returned.
+//Packs are freed.
+static float read_first_mpeg_pts_at_position(demuxer_t* demuxer, off_t stream_pos)
+{
+ stream_t *s = demuxer->stream;
+ mpg_demuxer_t *mpg_d = demuxer->priv;
+ float pts = -1.0; //the pts to return;
+ float found_pts1; //the most recently found pts
+ float found_pts2; //the pts found before found_pts1
+ float found_pts3; //the pts found before found_pts2
+ int found = 0;
+
+ if(!mpg_d || stream_pos < 0)
+ return pts;
+
+ found_pts3 = found_pts2 = found_pts1 = mpg_d->last_pts;
+ stream_seek(s, stream_pos);
+
+ //We look for pts.
+ //However, we do not stop at the first found one, as timestamps may reset
+ //Therefore, we seek until we found three consecutive
+ //pts within MAX_PTS_DIFF_FOR_CONSECUTIVE.
+
+ while(found<3 && !s->eof
+ && (fabsf(found_pts2-found_pts1) < MAX_PTS_DIFF_FOR_CONSECUTIVE)
+ && (fabsf(found_pts3-found_pts2) < MAX_PTS_DIFF_FOR_CONSECUTIVE)
+ && (stream_tell(s) < stream_pos + TIMESTAMP_PROBE_LEN)
+ && ds_fill_buffer(demuxer->video))
+ {
+ if(mpg_d->last_pts != found_pts1)
+ {
+ if(!found)
+ found_pts3 = found_pts2 = found_pts1 = mpg_d->last_pts; //the most recently found pts
+ else
+ {
+ found_pts3 = found_pts2;
+ found_pts2 = found_pts1;
+ found_pts1 = mpg_d->last_pts;
+ }
+ found++;
+ }
+ }
+
+ if(found == 3) pts = found_pts3;
+
+ //clean up from searching of first pts;
+ ds_free_packs(demuxer->audio);
+ ds_free_packs(demuxer->video);
+ ds_free_packs(demuxer->sub);
+
+ return pts;
+}
+
/// Open an mpg physical stream
static demuxer_t* demux_mpg_open(demuxer_t* demuxer) {
stream_t *s = demuxer->stream;
- off_t pos = stream_tell(s);
- off_t end_seq_start;
- float half_pts = 0.0;
mpg_demuxer_t* mpg_d;
if (!ds_fill_buffer(demuxer->video)) return 0;
- end_seq_start = demuxer->movi_end-TIMESTAMP_PROBE_LEN;
mpg_d = calloc(1,sizeof(mpg_demuxer_t));
- demuxer->priv = mpg_d;
- mpg_d->final_pts = 0.0;
- mpg_d->has_valid_timestamps = 1;
- mpg_d->num_a_streams = 0;
- if (demuxer->seekable && stream_tell(demuxer->stream) < end_seq_start) {
- off_t half_pos = pos + end_seq_start / 2;
- stream_seek(s, half_pos);
- while ((!s->eof) && ds_fill_buffer(demuxer->video) && half_pts == 0.0) {
- half_pts = mpg_d->last_pts;
- if (stream_tell(s) > half_pos + TIMESTAMP_PROBE_LEN)
- break;
- }
- stream_seek(s,end_seq_start);
- while ((!s->eof) && ds_fill_buffer(demuxer->video)) {
- if (mpg_d->final_pts < mpg_d->last_pts) mpg_d->final_pts = mpg_d->last_pts;
- if (stream_tell(s) > demuxer->movi_end)
- break;
- }
- // educated guess about validity of timestamps
- if (mpg_d->final_pts > 3 * half_pts || mpg_d->final_pts < 1.5 * half_pts) {
- mpg_d->has_valid_timestamps = 0;
- }
- ds_free_packs(demuxer->audio);
- ds_free_packs(demuxer->video);
- ds_free_packs(demuxer->sub);
- demuxer->stream->eof=0; // clear eof flag
- demuxer->video->eof=0;
- demuxer->audio->eof=0;
-
- stream_seek(s,pos);
- ds_fill_buffer(demuxer->video);
- }
+ if(mpg_d)
+ {
+ demuxer->priv = mpg_d;
+ mpg_d->last_pts = -1.0;
+ mpg_d->first_pts = -1.0;
+
+ //if seeking is allowed set has_valid_timestamps if appropriate
+ if(demuxer->seekable
+ && demuxer->stream->type == STREAMTYPE_FILE
+ && demuxer->movi_start != demuxer-> movi_end
+ )
+ {
+ //We seek to the beginning of the stream, to somewhere in the
+ //middle, and to the end of the stream, while remembering the pts
+ //at each of the three positions. With these pts, we check whether
+ //or not the pts are "linear enough" to justify seeking by the pts
+ //of the stream
+
+ //The position where the stream is now
+ off_t pos = stream_tell(s);
+ float first_pts = read_first_mpeg_pts_at_position(demuxer, demuxer->movi_start);
+ if(first_pts != -1.0)
+ {
+ float middle_pts = read_first_mpeg_pts_at_position(demuxer, (demuxer->movi_end - demuxer->movi_start)/2);
+ if(middle_pts != -1.0)
+ {
+ float final_pts = read_first_mpeg_pts_at_position(demuxer, demuxer->movi_end - TIMESTAMP_PROBE_LEN);
+ if(final_pts != -1.0)
+ {
+ // found proper first, middle, and final pts.
+ float proportion = (middle_pts-first_pts==0) ? -1 : (final_pts-middle_pts)/(middle_pts-first_pts);
+ // if they are linear enough set has_valid_timestamps
+ if((0.5 < proportion) && (proportion < 2))
+ {
+ mpg_d->first_pts = first_pts;
+ mpg_d->first_to_final_pts_len = final_pts - first_pts;
+ mpg_d->has_valid_timestamps = 1;
+ }
+ }
+ }
+ }
+
+ //Cleaning up from seeking in stream
+ demuxer->stream->eof=0;
+ demuxer->video->eof=0;
+ demuxer->audio->eof=0;
+
+ stream_seek(s,pos);
+ ds_fill_buffer(demuxer->video);
+ } // if ( demuxer->seekable )
+ } // if ( mpg_d )
return demuxer;
}
@@ -770,8 +846,8 @@ void demux_seek_mpg(demuxer_t *demuxer,float rel_seek_secs,float audio_delay, in
//================= seek in MPEG ==========================
//calculate the pts to seek to
if(flags & 2) {
- if (mpg_d && mpg_d->final_pts > 0.0)
- newpts += mpg_d->final_pts * rel_seek_secs;
+ if (mpg_d && mpg_d->first_to_final_pts_len > 0.0)
+ newpts += mpg_d->first_to_final_pts_len * rel_seek_secs;
else
newpts += rel_seek_secs * (demuxer->movi_end - demuxer->movi_start) * oldpts / oldpos;
} else
@@ -784,8 +860,8 @@ void demux_seek_mpg(demuxer_t *demuxer,float rel_seek_secs,float audio_delay, in
} else {
// time seek (secs)
if (mpg_d && mpg_d->has_valid_timestamps) {
- if (mpg_d->final_pts > 0.0)
- newpos += rel_seek_secs * (demuxer->movi_end - demuxer->movi_start) / mpg_d->final_pts;
+ if (mpg_d->first_to_final_pts_len > 0.0)
+ newpos += rel_seek_secs * (demuxer->movi_end - demuxer->movi_start) / mpg_d->first_to_final_pts_len;
else if (oldpts > 0.0)
newpos += rel_seek_secs * (oldpos - demuxer->movi_start) / oldpts;
} else if(!sh_video || !sh_video->i_bps) // unspecified or VBR
@@ -871,14 +947,14 @@ int demux_mpg_control(demuxer_t *demuxer,int cmd, void *arg){
return DEMUXER_CTRL_GUESS;
}
if (mpg_d && mpg_d->has_valid_timestamps) {
- *((double *)arg)=(double)mpg_d->final_pts;
- return DEMUXER_CTRL_GUESS;
+ *((double *)arg)=(double)mpg_d->first_to_final_pts_len;
+ return DEMUXER_CTRL_OK;
}
return DEMUXER_CTRL_DONTKNOW;
case DEMUXER_CTRL_GET_PERCENT_POS:
- if (mpg_d && mpg_d->has_valid_timestamps && mpg_d->final_pts > 0.0) {
- *((int *)arg)=(int)(100 * mpg_d->last_pts / mpg_d->final_pts);
+ if (mpg_d && mpg_d->has_valid_timestamps && mpg_d->first_to_final_pts_len > 0.0) {
+ *((int *)arg)=(int)(100 * (mpg_d->last_pts-mpg_d->first_pts) / mpg_d->first_to_final_pts_len);
return DEMUXER_CTRL_OK;
}
return DEMUXER_CTRL_DONTKNOW;
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-17 21:34:00 +0000