From e78d0810d1741535c95e5ae0f198977626b1cdff Mon Sep 17 00:00:00 2001 From: Gustav Grusell Date: Fri, 28 Jan 2022 21:23:20 +0100 Subject: avformat/hls: Implement support for using AVSEEK_FLAG_BACKWARD when seeking Before, seeking in hls streams would always seek to the next keyframe after the given timestamp. With this fix, if seeking in videostream and AVSEEK_FLAG_BACKWARD is set, seeking will be to the first keyframe of the segment containing the given timestamp. This fixes #7485. Signed-off-by: Gustav Grusell --- libavformat/hls.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) (limited to 'libavformat') diff --git a/libavformat/hls.c b/libavformat/hls.c index 4568e72cb2..44afdaab42 100644 --- a/libavformat/hls.c +++ b/libavformat/hls.c @@ -1653,7 +1653,8 @@ static void add_metadata_from_renditions(AVFormatContext *s, struct playlist *pl /* if timestamp was in valid range: returns 1 and sets seq_no * if not: returns 0 and sets seq_no to closest segment */ static int find_timestamp_in_playlist(HLSContext *c, struct playlist *pls, - int64_t timestamp, int64_t *seq_no) + int64_t timestamp, int64_t *seq_no, + int64_t *seg_start_ts) { int i; int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? @@ -1668,6 +1669,9 @@ static int find_timestamp_in_playlist(HLSContext *c, struct playlist *pls, int64_t diff = pos + pls->segments[i]->duration - timestamp; if (diff > 0) { *seq_no = pls->start_seq_no + i; + if (seg_start_ts) { + *seg_start_ts = pos; + } return 1; } pos += pls->segments[i]->duration; @@ -1691,7 +1695,7 @@ static int64_t select_cur_seq_no(HLSContext *c, struct playlist *pls) * playlist) and this is a complete file, find the matching segment * by counting durations. */ if (pls->finished && c->cur_timestamp != AV_NOPTS_VALUE) { - find_timestamp_in_playlist(c, pls, c->cur_timestamp, &seq_no); + find_timestamp_in_playlist(c, pls, c->cur_timestamp, &seq_no, NULL); return seq_no; } @@ -2362,7 +2366,7 @@ static int hls_read_seek(AVFormatContext *s, int stream_index, int i, j; int stream_subdemuxer_index; int64_t first_timestamp, seek_timestamp, duration; - int64_t seq_no; + int64_t seq_no, seg_start_ts; if ((flags & AVSEEK_FLAG_BYTE) || (c->ctx->ctx_flags & AVFMTCTX_UNSEEKABLE)) return AVERROR(ENOSYS); @@ -2372,8 +2376,7 @@ static int hls_read_seek(AVFormatContext *s, int stream_index, seek_timestamp = av_rescale_rnd(timestamp, AV_TIME_BASE, s->streams[stream_index]->time_base.den, - flags & AVSEEK_FLAG_BACKWARD ? - AV_ROUND_DOWN : AV_ROUND_UP); + AV_ROUND_DOWN); duration = s->duration == AV_NOPTS_VALUE ? 0 : s->duration; @@ -2394,9 +2397,16 @@ static int hls_read_seek(AVFormatContext *s, int stream_index, } /* check if the timestamp is valid for the playlist with the * specified stream index */ - if (!seek_pls || !find_timestamp_in_playlist(c, seek_pls, seek_timestamp, &seq_no)) + if (!seek_pls || !find_timestamp_in_playlist(c, seek_pls, seek_timestamp, &seq_no, &seg_start_ts)) return AVERROR(EIO); + if (s->streams[stream_index]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && + flags & AVSEEK_FLAG_BACKWARD && !(flags & AVSEEK_FLAG_ANY)) { + /* Seeking to start of segment ensures we seek to a keyframe located + * before the given timestamp. */ + seek_timestamp = seg_start_ts; + } + /* set segment now so we do not need to search again below */ seek_pls->cur_seq_no = seq_no; seek_pls->seek_stream_index = stream_subdemuxer_index; @@ -2423,7 +2433,7 @@ static int hls_read_seek(AVFormatContext *s, int stream_index, if (pls != seek_pls) { /* set closest segment seq_no for playlists not handled above */ - find_timestamp_in_playlist(c, pls, seek_timestamp, &pls->cur_seq_no); + find_timestamp_in_playlist(c, pls, seek_timestamp, &pls->cur_seq_no, NULL); /* seek the playlist to the given position without taking * keyframes into account since this playlist does not have the * specified stream where we should look for the keyframes */ -- cgit v1.2.3