lavf/subtitles: add ff_subtitles_queue_seek().

This function is almost identical to lavf/assdec:read_seek2(). It
performs a generic seek for text subtitles demuxers for the new seeking
API.

The only difference with assdec:read_seek2 is the ts_diff being
unsigned to avoid overflows.

The seek callback in the ASS demuxer will be removed when it is
redesigned to use FFDemuxSubtitlesQueue.

1 files changed, 7 insertions, 0 deletions

diff --git a/libavformat/subtitles.h b/libavformat/subtitles.h
index b089bb2a87..55e6182922 100644
--- a/libavformat/subtitles.h
+++ b/libavformat/subtitles.h
@@ -55,6 +55,13 @@ void ff_subtitles_queue_finalize(FFDemuxSubtitlesQueue *q);
 int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt);
 
 /**
+ * Update current_sub_idx to emulate a seek. Except the first parameter, it
+ * matches AVInputFormat->read_seek2 prototypes.
+ */
+int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
+                            int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
+
+/**
  * Remove and destroy all the subtitles packets.
  */
 void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q);