[FFmpeg-devel] [PATCH] avformat/hls Implement support for using AVSEEK_FLAG_BACKWARD when seeking

[Gustav Grusell]

Before, seeking in hls streams would always seek to the next keyframe after the given timestamp.
With this fix, if 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 <gustav.grusell at gmail.com>
---
 libavformat/hls.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libavformat/hls.c b/libavformat/hls.c
index 8fc6924c90..fb8c9b071a 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -2197,6 +2197,15 @@ static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
                         break;
                     }
 
+                    /* If AVSEEK_FLAG_BACKWARD set and not AVSEEK_FLAG_ANY,
+                     * we return the first keyframe encountered */
+                    if (pls->seek_flags & AVSEEK_FLAG_BACKWARD &&
+                        !(pls->seek_flags & AVSEEK_FLAG_ANY) &&
+                        pls->pkt->flags & AV_PKT_FLAG_KEY) {
+                        pls->seek_timestamp = AV_NOPTS_VALUE;
+                        break;
+                    }
+
                     tb = get_timebase(pls);
                     ts_diff = av_rescale_rnd(pls->pkt->dts, AV_TIME_BASE,
                                             tb.den, AV_ROUND_DOWN) -
-- 
2.25.1