[FFmpeg-devel] [PATCH] avformat/mov: fix sidx timestamp handling, use PTS instead of DTS

[FFmpeg-devel] [PATCH] avformat/mov: fix sidx timestamp handling, use PTS instead of DTS

[Vivek Jain via ffmpeg-devel]

The 'sidx' earliest_presentation_time field is defined as PTS. Previously, it was incorrectly assigned to DTS, which could cause sync issues. This commit fixes the assignment to PTS as noted in the existing FIXME comment.
---
 libavformat/mov.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 009ddfec80..f651d0387b 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5892,9 +5892,9 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
             } else if (has_sidx && !c->use_tfdt || fallback_sidx) {
                 // FIXME: sidx earliest_presentation_time is *PTS*, s.b.
                 // pts = frag_stream_info->sidx_pts;
-                dts = frag_stream_info->sidx_pts;
+                pts = frag_stream_info->sidx_pts; // <--- FIXED
                 av_log(c->fc, AV_LOG_DEBUG, "found sidx time %"PRId64
-                        ", using it for dts\n", frag_stream_info->sidx_pts);
+                        ", using it for pts\n", frag_stream_info->sidx_pts); // Update log message too if you like, but logically just changing to pts is the key.
             } else {
                 dts = sc->track_end - sc->time_offset;
                 av_log(c->fc, AV_LOG_DEBUG, "found track end time %"PRId64
-- 
2.49.0.windows.1


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[FFmpeg-devel] Re: [PATCH] avformat/mov: fix sidx timestamp handling, use PTS instead of DTS

[Michael Niedermayer via ffmpeg-devel]

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Hi Vivek

On Wed, Dec 31, 2025 at 05:41:22PM +0530, Vivek Jain via ffmpeg-devel wrote:
> The 'sidx' earliest_presentation_time field is defined as PTS. Previously, it was incorrectly assigned to DTS, which could cause sync issues. This commit fixes the assignment to PTS as noted in the existing FIXME comment.
> ---
>  libavformat/mov.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 009ddfec80..f651d0387b 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -5892,9 +5892,9 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>              } else if (has_sidx && !c->use_tfdt || fallback_sidx) {
>                  // FIXME: sidx earliest_presentation_time is *PTS*, s.b.
>                  // pts = frag_stream_info->sidx_pts;
> -                dts = frag_stream_info->sidx_pts;
> +                pts = frag_stream_info->sidx_pts; // <--- FIXED

This taken as a whole is wrong.

First step is explaining why there is a FIXME comment and outcommented code
only after that is understood can this be fixed, but either way
the fixme and fix cannot co-exist. Either its fixed or not

also the last change to this line should be considered 0de3b1f3588e1fc9e292098902ac79d8dd9792bc


>                  av_log(c->fc, AV_LOG_DEBUG, "found sidx time %"PRId64
> -                        ", using it for dts\n", frag_stream_info->sidx_pts);
> +                        ", using it for pts\n", frag_stream_info->sidx_pts); // Update log message too if you like, but logically just changing to pts is the key.
>              } else {

This comment is not usefull

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

What is money laundering? Its paying someone and not telling the government.

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