[FFmpeg-cvslog] libavformat: Account for negative position differences in ff_configure_buffers_for_index

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Fri Mar 24 23:08:10 2023 +0200| [33d06de6381aeaf0e6281f8ba0a39ed3bfda19fa] | committer: Martin Storsjö

libavformat: Account for negative position differences in ff_configure_buffers_for_index

When scanning through the index, account for the fact that the
compared samples may be located in an unexpected order in the file;
this function is mainly interested in the absolute difference between
file locations.

Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=33d06de6381aeaf0e6281f8ba0a39ed3bfda19fa
---

 libavformat/seek.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/seek.c b/libavformat/seek.c
index a236e285c0..faa47f961f 100644
--- a/libavformat/seek.c
+++ b/libavformat/seek.c
@@ -208,9 +208,11 @@ void ff_configure_buffers_for_index(AVFormatContext *s, int64_t time_tolerance)
                 for (; i2 < sti2->nb_index_entries; i2++) {
                     const AVIndexEntry *const e2 = &sti2->index_entries[i2];
                     int64_t e2_pts = av_rescale_q(e2->timestamp, st2->time_base, AV_TIME_BASE_Q);
+                    int64_t cur_delta;
                     if (e2_pts < e1_pts || e2_pts - (uint64_t)e1_pts < time_tolerance)
                         continue;
-                    pos_delta = FFMAX(pos_delta, e1->pos - e2->pos);
+                    cur_delta = FFABS(e1->pos - e2->pos);
+                    pos_delta = FFMAX(pos_delta, cur_delta);
                     break;
                 }
             }