demux: make determining seek capability generic

Instead of having each demuxer do it (only demux_mkv actually did...),
let generic code determine whether the file is seekable. This requires
adding exceptions to demuxers where the stream is not seekable, but the
demuxer is.

Sort-of try to improve handling of unseekable files in the player. Exit
early if the file is determined to be unseekable, instead of resetting
all decoders and then performing a pointless seek.

Add an exception to allow seeking if the file is not seekable, but the
stream cache is enabled. Print a warning in this case, because seeking
outside the cache (which we can't prevent since the demuxer is not aware
of this problem) still messes everything up.

1 files changed, 5 insertions, 0 deletions

diff --git a/mpvcore/player/playloop.c b/mpvcore/player/playloop.c
index 9e5aa1e0b4..90525a5ca2 100644
--- a/mpvcore/player/playloop.c
+++ b/mpvcore/player/playloop.c
@@ -215,6 +215,11 @@ static int seek(MPContext *mpctx, struct seek_params seek,
     if (!mpctx->demuxer)
         return -1;
 
+    if (!mpctx->demuxer->seekable) {
+        MP_ERR(mpctx, "Can't seek in this file.\n");
+        return -1;
+    }
+
     if (mpctx->stop_play == AT_END_OF_FILE)
         mpctx->stop_play = KEEP_PLAYING;
     bool hr_seek = mpctx->demuxer->accurate_seek && opts->correct_pts;