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sd_lavc: discard empty subtitles and improve sub_seek behavior 

Image subtitles often use a "signaling" packet to set the end time of
the previous subtitle. As far as the libavcodec API is concerned, such
packets decode to empty AVSubtitles. Discard these after the end time of
the previous subtitle has been set.

Keep track of the per-subtitle end time better. This is for the sake of
improving sub_step/sub_seek. Without this, it would seek to the sub
before the previous sub, if the current sub has ended displaying.
This commit is contained in:
wm4 2015-12-05 23:55:35 +01:00
parent a7cf091519
commit 9a240dc82e
1 changed files with 49 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
sub/sd_lavc.c
View File

@ -46,6 +46,11 @@ struct sub {
int64_t id;
};
struct seekpoint {
double pts;
double endpts;
};
struct sd_lavc_priv {
AVCodecContext *avctx;
struct sub subs[MAX_QUEUE]; // most recent event first
@ -54,8 +59,8 @@ struct sd_lavc_priv {
int64_t new_id;
struct mp_image_params video_params;
double current_pts;
double *timestamps;
int num_timestamps;
struct seekpoint *seekpoints;
int num_seekpoints;
};
static bool supports_format(const char *format)
@ -158,6 +163,7 @@ static void decode(struct sd *sd, struct demux_packet *packet)
struct sd_lavc_priv *priv = sd->priv;
AVCodecContext *ctx = priv->avctx;
double pts = packet->pts;
double endpts = MP_NOPTS_VALUE;
double duration = packet->duration;
AVSubtitle sub;
AVPacket pkt;
@ -186,14 +192,30 @@ static void decode(struct sd *sd, struct demux_packet *packet)
duration = (sub.end_display_time - sub.start_display_time) / 1000.0;
}
pts += sub.start_display_time / 1000.0;
}
double endpts = MP_NOPTS_VALUE;
if (pts != MP_NOPTS_VALUE && duration >= 0)
endpts = pts + duration;
// set end time of previous sub
if (priv->subs[0].endpts == MP_NOPTS_VALUE || priv->subs[0].endpts > pts)
priv->subs[0].endpts = pts;
if (duration >= 0)
endpts = pts + duration;
// set end time of previous sub
struct sub *prev = &priv->subs[0];
if (prev->valid) {
if (prev->endpts == MP_NOPTS_VALUE || prev->endpts > pts)
prev->endpts = pts;
for (int n = 0; n < priv->num_seekpoints; n++) {
if (priv->seekpoints[n].pts == prev->pts) {
priv->seekpoints[n].endpts = prev->endpts;
break;
}
}
}
// This subtitle packet only signals the end of subtitle display.
if (!sub.num_rects) {
avsubtitle_free(&sub);
return;
}
}
alloc_sub(priv);
struct sub *current = &priv->subs[0];
@ -238,15 +260,16 @@ static void decode(struct sd *sd, struct demux_packet *packet)
current->count++;
}
if (pts != MP_NOPTS_VALUE && current->count) {
for (int n = 0; n < priv->num_timestamps; n++) {
if (priv->timestamps[n] == pts)
if (pts != MP_NOPTS_VALUE) {
for (int n = 0; n < priv->num_seekpoints; n++) {
if (priv->seekpoints[n].pts == pts)
goto skip;
}
// Set arbitrary limit as safe-guard against insane files.
if (priv->num_timestamps >= 10000)
MP_TARRAY_REMOVE_AT(priv->timestamps, priv->num_timestamps, 0);
MP_TARRAY_APPEND(priv, priv->timestamps, priv->num_timestamps, pts);
if (priv->num_seekpoints >= 10000)
MP_TARRAY_REMOVE_AT(priv->seekpoints, priv->num_seekpoints, 0);
MP_TARRAY_APPEND(priv, priv->seekpoints, priv->num_seekpoints,
(struct seekpoint){.pts = pts, .endpts = endpts});
skip: ;
}
}
@ -363,10 +386,10 @@ static void uninit(struct sd *sd)
talloc_free(priv);
}
static int compare_double(const void *pa, const void *pb)
static int compare_seekpoint(const void *pa, const void *pb)
{
double diff = *(double *)pa - *(double *)pb;
return diff == 0 ? 0 : (diff < 0 ? -1 : +1);
const struct seekpoint *a = pa, *b = pb;
return a->pts == b->pts ? 0 : (a->pts < b->pts ? -1 : +1);
}
// taken from ass_step_sub(), libass (ISC)
@ -377,21 +400,20 @@ static double step_sub(struct sd *sd, double now, int movement)
double target = now;
int direction = movement > 0 ? 1 : -1;
if (movement == 0 || priv->num_timestamps == 0)
if (movement == 0 || priv->num_seekpoints == 0)
return MP_NOPTS_VALUE;
qsort(priv->timestamps, priv->num_timestamps, sizeof(priv->timestamps[0]),
compare_double);
qsort(priv->seekpoints, priv->num_seekpoints, sizeof(priv->seekpoints[0]),
compare_seekpoint);
while (movement) {
int closest = -1;
double closest_time = 0;
for (int i = 0; i < priv->num_timestamps; i++) {
double start = priv->timestamps[i];
for (int i = 0; i < priv->num_seekpoints; i++) {
struct seekpoint *p = &priv->seekpoints[i];
double start = p->pts;
if (direction < 0) {
double end = start;
if (i + 1 < priv->num_timestamps)
end = priv->timestamps[i + 1];
double end = p->endpts == MP_NOPTS_VALUE ? INFINITY : p->endpts;
if (end < target) {
if (closest < 0 || end > closest_time) {
closest = i;
@ -414,7 +436,7 @@ static double step_sub(struct sd *sd, double now, int movement)
movement -= direction;
}
return best < 0 ? 0 : priv->timestamps[best] - now;
return best < 0 ? 0 : priv->seekpoints[best].pts - now;
}
static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)