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Add improved relative seek mode 

When the new mode is active relative seeks are converted to absolute
ones (current video pts + relative seek amount) and forward/backward
flag before being sent to the demuxer. This mode is used if the
demuxer has set the accurate_seek field in the demuxer struct and
there is a video stream. At the moment the mkv and lavf demuxers
enable the flag.

This change is useful for later Matroska ordered chapter support (and
for more general timelime editing), but also fixes problems in
existing functionality. The main problem with the old mode, where
relative seeks are passed directly to the demuxer, is that the user
wants to seek relative to the currently displayed position but the
demuxer does not know what that position is. There can be an arbitrary
amount of buffering between the demuxer read position and what is
displayed on the screen. In some situations this makes small seeks
fail to move backward at all (especially visible at high playback
speed, when audio needs to be demuxed and decoded further ahead to
fill the output buffers after resampling).

Some container formats that can be used with the lavf demuxer do not
always have reliable timestamps that could be used for unambiguous
absolute seeking. However I made the demuxer always enable the new
mode because it already converted all seeks to absolute ones before
sending them to libavformat, so cases without reliable absolute seeks
were failing already and this should only improve the working cases.
This commit is contained in:
Uoti Urpala 2009-03-19 05:25:12 +02:00
parent 3279403611
commit 73fb23c1cf
4 changed files with 39 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
libmpdemux/demux_lavf.c
View File

@ -22,6 +22,7 @@
#include <stdlib.h>
// #include <unistd.h>
#include <limits.h>
#include <stdbool.h>
#include "config.h"
#include "options.h"
@ -533,6 +534,8 @@ static demuxer_t* demux_open_lavf(demuxer_t *demuxer){
demuxer->video->id=-2; // audio-only
} //else if (best_video > 0 && demuxer->video->id == -1) demuxer->video->id = best_video;
demuxer->accurate_seek = true;
return demuxer;
}
@ -612,6 +615,10 @@ static void demux_seek_lavf(demuxer_t *demuxer, float rel_seek_secs, float audio
} else {
if (rel_seek_secs < 0) avsflags = AVSEEK_FLAG_BACKWARD;
}
if (flags & SEEK_FORWARD)
avsflags = 0;
else if (flags & SEEK_BACKWARD)
avsflags = AVSEEK_FLAG_BACKWARD;
if (flags & SEEK_FACTOR) {
if (priv->avfc->duration == 0 || priv->avfc->duration == AV_NOPTS_VALUE)
return;

24
libmpdemux/demux_mkv.c
View File

@ -2295,6 +2295,8 @@ demux_mkv_open (demuxer_t *demuxer)
demuxer->seekable = 1;
}
demuxer->accurate_seek = true;
return DEMUXER_TYPE_MATROSKA;
}
@ -2962,6 +2964,12 @@ demux_mkv_fill_buffer (demuxer_t *demuxer, demux_stream_t *ds)
static void
demux_mkv_seek (demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int flags)
{
if (!(flags & (SEEK_BACKWARD | SEEK_FORWARD))) {
if (flags & SEEK_ABSOLUTE || rel_seek_secs < 0)
flags |= SEEK_BACKWARD;
else
flags |= SEEK_FORWARD;
}
free_cached_dps (demuxer);
if (!(flags & SEEK_FACTOR)) /* time in secs */
{
@ -3016,12 +3024,12 @@ demux_mkv_seek (demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int
for (i=0; i < mkv_d->num_cluster_pos; i++)
{
diff = mkv_d->cluster_positions[i] - target_filepos;
if (rel_seek_secs < 0 && diff < 0 && -diff < min_diff)
if (flags & SEEK_BACKWARD && diff < 0 && -diff < min_diff)
{
cluster_pos = mkv_d->cluster_positions[i];
min_diff = -diff;
}
else if (rel_seek_secs > 0
else if (flags & SEEK_FORWARD
&& (diff < 0 ? -1 * diff : diff) < min_diff)
{
cluster_pos = mkv_d->cluster_positions[i];
@ -3045,14 +3053,14 @@ demux_mkv_seek (demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int
diff = target_timecode + mkv_d->first_tc -
(int64_t) mkv_d->indexes[i].timecode * mkv_d->tc_scale / 1000000.0;
if ((flags & SEEK_ABSOLUTE || target_timecode <= mkv_d->last_pts*1000)) {
// Absolute seek or seek backward: find the last index
// position before target time
if (flags & SEEK_BACKWARD) {
// Seek backward: find the last index position
// before target time
if (diff < 0 || diff >= min_diff)
continue;
}
else {
// Relative seek forward: find the first index position
// Seek forward: find the first index position
// after target time. If no such index exists, find last
// position between current position and target time.
if (diff <= 0) {
@ -3076,8 +3084,10 @@ demux_mkv_seek (demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int
if (demuxer->video->id >= 0)
mkv_d->v_skip_to_keyframe = 1;
if (rel_seek_secs > 0.0)
if (flags & SEEK_FORWARD)
mkv_d->skip_to_timecode = target_timecode;
else
mkv_d->skip_to_timecode = 0;
mkv_d->a_skip_to_keyframe = 1;
demux_mkv_fill_buffer(demuxer, NULL);

5
libmpdemux/demuxer.h
View File

@ -96,6 +96,8 @@ struct MPOpts;
#define SEEK_ABSOLUTE (1 << 0)
#define SEEK_FACTOR (1 << 1)
#define SEEK_FORWARD (1 << 2)
#define SEEK_BACKWARD (1 << 3)
#define MP_INPUT_BUFFER_PADDING_SIZE 8
@ -221,6 +223,9 @@ typedef struct demuxer {
int type; // demuxer type: mpeg PS, mpeg ES, avi, avi-ni, avi-nini, asf
int file_format; // file format: mpeg/avi/asf
int seekable; // flag
/* Set if using absolute seeks for small movements is OK (no pts resets
* that would make pts ambigious, preferably supports back/forward flags */
bool accurate_seek;
//
demux_stream_t *audio; // audio buffer/demuxer
demux_stream_t *video; // video buffer/demuxer

10
mplayer.c
View File

@ -2463,6 +2463,16 @@ static void edl_update(MPContext *mpctx)
static int seek(MPContext *mpctx, double amount, int style)
{
current_module = "seek";
if (mpctx->demuxer->accurate_seek && mpctx->sh_video
&& !(style & (SEEK_ABSOLUTE | SEEK_FACTOR))) {
style |= SEEK_ABSOLUTE;
if (amount > 0)
style |= SEEK_FORWARD;
else
style |= SEEK_BACKWARD;
amount += mpctx->sh_video->pts;
}
if (demux_seek(mpctx->demuxer, amount, audio_delay, style) == 0)
return -1;