PR #20717 opened by frankplow URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20717 Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20717.patch
seq_decode is used to ensure that a picture and all of its reference pictures use the same SPS. Any time the SPS changes, seq_decode should be incremented. Prior to this patch, seq_decode was incremented in frame_context_setup, which is called after the SPS is potentially changed in decode_sps. Should the decoder encounter an error between changing the SPS and incrementing seq_decode, the SPS could be modified while seq_decode was not incremented, which could lead to invalid reference pictures and various downstream issues. By instead updating seq_decode within the picture set manager, we ensure seq_decode and the SPS are always updated in tandem. >From e611aeff64a15d12cede6da420e0173c665117a7 Mon Sep 17 00:00:00 2001 From: Frank Plowman <[email protected]> Date: Sun, 19 Oct 2025 12:28:00 +0100 Subject: [PATCH] lavc/vvc: Ensure seq_decode is always updated with SPS seq_decode is used to ensure that a picture and all of its reference pictures use the same SPS. Any time the SPS changes, seq_decode should be incremented. Prior to this patch, seq_decode was incremented in frame_context_setup, which is called after the SPS is potentially changed in decode_sps. Should the decoder encounter an error between changing the SPS and incrementing seq_decode, the SPS could be modified while seq_decode was not incremented, which could lead to invalid reference pictures and various downstream issues. By instead updating seq_decode within the picture set manager, we ensure seq_decode and the SPS are always updated in tandem. --- libavcodec/vvc/dec.c | 1 - libavcodec/vvc/ps.c | 2 ++ 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/libavcodec/vvc/dec.c b/libavcodec/vvc/dec.c index bfe330e028..028f34b491 100644 --- a/libavcodec/vvc/dec.c +++ b/libavcodec/vvc/dec.c @@ -726,7 +726,6 @@ static int frame_context_setup(VVCFrameContext *fc, VVCContext *s) } if (IS_IDR(s)) { - s->seq_decode = (s->seq_decode + 1) & 0xff; ff_vvc_clear_refs(fc); } diff --git a/libavcodec/vvc/ps.c b/libavcodec/vvc/ps.c index 8faee1d826..a591851238 100644 --- a/libavcodec/vvc/ps.c +++ b/libavcodec/vvc/ps.c @@ -279,12 +279,14 @@ fail: static int decode_sps(VVCParamSets *ps, AVCodecContext *c, const H266RawSPS *rsps, int is_clvss) { + VVCContext *s = c->priv_data; const int sps_id = rsps->sps_seq_parameter_set_id; const VVCSPS *old_sps = ps->sps_list[sps_id]; const VVCSPS *sps; if (is_clvss) { ps->sps_id_used = 0; + s->seq_decode = (s->seq_decode + 1) & 0xff; } if (old_sps) { -- 2.49.1 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
