player: improve instant track switching

When switching tracks, we normally have the problem that data gets lost
due to readahead buffering. (Which in turn is because we're stubborn and
instruct the demuxers to discard data on unselected streams.) The
demuxer layer has a hack that re-reads discarded buffered data if a
stream is enabled mid-stream, so track switching will seem instant.

A somewhat similar problem is when all tracks of an external files were
disabled - when enabling the first track, we have to seek to the target
position.

Handle these with the same mechanism. Pass the "current time" to the
demuxer's stream switch function, and let the demuxer figure out what to
do. The demuxer will issue a refresh seek (if possible) to update the
new stream, or will issue a "normal" seek if there was no active stream
yet.

One case that changes is when a video/audio stream is enabled on an
external file with only a subtitle stream active, and the demuxer does
not support rrefresh seeks. This is a fuzzy case, because subtitles are
sparse, and the demuxer might have skipped large amounts of data. We
used to seek (and send the subtitle decoder some subtitle packets
twice). This case is sort of obscure and insane, and the fix would be
questionable, so we simply don't care.

Should mostly fix #3392.

1 files changed, 1 insertions, 2 deletions

diff --git a/demux/demux.h b/demux/demux.h
index a26dada6c8..8c07fe8933 100644
--- a/demux/demux.h
+++ b/demux/demux.h
@@ -265,13 +265,12 @@ bool demux_cancel_test(struct demuxer *demuxer);
 
 void demux_flush(struct demuxer *demuxer);
 int demux_seek(struct demuxer *demuxer, double rel_seek_secs, int flags);
-void demux_set_enable_refresh_seeks(struct demuxer *demuxer, bool enabled);
 void demux_set_ts_offset(struct demuxer *demuxer, double offset);
 
 int demux_control(struct demuxer *demuxer, int cmd, void *arg);
 
 void demuxer_select_track(struct demuxer *demuxer, struct sh_stream *stream,
-                          bool selected);
+                          double ref_pts, bool selected);
 void demux_set_stream_autoselect(struct demuxer *demuxer, bool autoselect);
 
 void demuxer_help(struct mp_log *log);