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demux_disc: handle slideshow DVD titles

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Audio DVDs commonly author each song as a chapter whose video is a
single (or more) still frame, with only the audio really interleaved.
Detect this at runtime and mark the video still_image. The player then
treats it as sparse, and the starved stream stops forcing eager reads
that would scan through the source hunting for the next still.
This commit is contained in:
Kacper Michajłow committed 2026-08-26 01:47:41 +02:00
1 parent 4109805d0c
commit fee9b14d46
1 file changed
+77 -4
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demux/demux_disc.c
+77 -4
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@@ -70,12 +70,20 @@ struct priv {
uint32_t last_discontinuity_id; // Last source-position-jump id seen from the stream.
bool nav_active; // last interactive-nav state pushed to the cache
bool is_dvd, is_cdda, is_bd;
bool is_dvd, is_dvda, is_cdda, is_bd;
// DVD-Audio still-image video track.
struct sh_stream *still_sh;
int last_still_id;
struct demux_packet *pending_pkt; // still or the audio deferred behind it
// Sparse-video (slideshow title) detection state.
struct sh_stream *video_sh;
double last_video_dts;
// Seeks into sparse-video titles land at the preceding chapter start,
// where the target's still frame is. Drop audio until this target.
double skip_audio_until;
};
static void clear_dvd_sub_holds(struct priv *p)
@@ -380,12 +388,36 @@ static void d_seek(demuxer_t *demuxer, double seek_pts, int flags)
bool have_nav = stream_control(demuxer->stream, STREAM_CTRL_GET_NAV_STATE, &nav) >= 1;
bool resync = have_nav && nav.drain_pending;
p->skip_audio_until = MP_NOPTS_VALUE;
if (resync) {
MP_VERBOSE(demuxer, "resync seek at jump boundary (disc id %u)\n",
nav.discontinuity_id);
} else {
MP_VERBOSE(demuxer, "seek to: %f\n", seek_pts);
double seek_arg[] = {seek_pts, flags};
// In slideshow titles the target's still lies at the preceding
// chapter (cell) start and can't be read backwards from a mid-cell
// landing. Land there and drop audio up to the actual target.
double stream_target = seek_pts;
int stream_flags = flags;
if (p->video_sh && p->video_sh->still_image &&
demuxer->num_chapters > 0)
{
double snap = 0;
for (int n = 0; n < demuxer->num_chapters; n++) {
double c = demuxer->chapters[n].pts;
if (c <= seek_pts && c > snap)
snap = c;
}
if (seek_pts - snap > 0.5) {
MP_VERBOSE(demuxer, "sparse video: landing at chapter start %f, "
"skipping audio to %f\n", snap, seek_pts);
stream_target = snap;
stream_flags &= ~(unsigned)SEEK_HR; // landing is chosen exactly
p->skip_audio_until = seek_pts;
}
}
MP_VERBOSE(demuxer, "seek to: %f\n", stream_target);
double seek_arg[] = {stream_target, stream_flags};
stream_control(demuxer->stream, STREAM_CTRL_SEEK_TO_TIME, seek_arg);
}
@@ -421,6 +453,7 @@ static void reset_pts(demuxer_t *demuxer)
p->base_dts = p->last_dts = MP_NOPTS_VALUE;
p->base_time = base;
p->last_video_dts = MP_NOPTS_VALUE;
p->seek_reinit = false;
}
@@ -678,7 +711,8 @@ static bool d_read_packet(struct demuxer *demuxer, struct demux_packet **out_pkt
p->last_dts = pkt->dts;
if (fabs(p->last_dts - pkt->dts) >= DTS_RESET_THRESHOLD) {
MP_VERBOSE(demuxer, "PTS discontinuity: %f->%f\n", p->last_dts, pkt->dts);
MP_VERBOSE(demuxer, "PTS discontinuity: %f->%f (%s)\n",
p->last_dts, pkt->dts, stream_type_name(sh->type));
p->base_time += p->last_dts - p->base_dts;
p->base_dts = pkt->dts;
if (pkt->duration > 0)
@@ -698,6 +732,42 @@ static bool d_read_packet(struct demuxer *demuxer, struct demux_packet **out_pkt
MP_TRACE(demuxer, "mapped pkt: type=%d pts=%f dts=%f\n",
sh->type, pkt->pts, pkt->dts);
// Detect slideshow video, one still per song on audio DVDs. Audio
// running several seconds past the last video packet cannot happen with
// really interleaved video.
if ((p->is_dvd || p->is_dvda) && pkt->dts != MP_NOPTS_VALUE) {
if (sh->type == STREAM_VIDEO) {
p->video_sh = sh;
p->last_video_dts = pkt->dts;
} else if (sh->type == STREAM_AUDIO && p->video_sh &&
!p->video_sh->still_image &&
demux_stream_is_selected(p->video_sh) &&
p->last_video_dts != MP_NOPTS_VALUE &&
pkt->dts - p->last_video_dts > 5.0)
{
MP_VERBOSE(demuxer, "no video for %.1fs while audio advances; "
"marking video as sparse still images\n",
pkt->dts - p->last_video_dts);
// Stop the starved video stream from forcing eager reads (it
// would race through the source hunting for the next still).
demux_set_stream_still_image(demuxer, p->video_sh, true);
}
}
// Drop audio between the chapter-start landing and the seek target
// (see d_seek).
if (p->skip_audio_until != MP_NOPTS_VALUE && sh->type == STREAM_AUDIO &&
pkt->pts != MP_NOPTS_VALUE)
{
if (pkt->pts < p->skip_audio_until) {
talloc_free(pkt);
return true;
}
MP_VERBOSE(demuxer, "audio reached seek target %f\n",
p->skip_audio_until);
p->skip_audio_until = MP_NOPTS_VALUE;
}
if (sh->type == STREAM_AUDIO && pkt->pts != MP_NOPTS_VALUE) {
inject_still(demuxer, pkt->pts);
// Deliver the still before the audio it belongs to, so the frame is
@@ -809,8 +879,11 @@ static int d_open(demuxer_t *demuxer, enum demux_check check)
p->is_cdda = strcmp(sname, "cdda") == 0;
p->is_dvd = strcmp(sname, "dvdnav") == 0 ||
strcmp(sname, "ifo_dvdnav") == 0;
p->is_dvda = strcmp(sname, "dvda") == 0 ||
strcmp(sname, "ifo_dvda") == 0;
p->is_bd = strcmp(sname, "bd") == 0 ||
strcmp(sname, "bdmv/bluray") == 0;
p->skip_audio_until = MP_NOPTS_VALUE;
if (p->is_cdda)
params.force_format = "+rawaudio";