[FFmpeg-devel] [PATCH] lavf: vvc_probe: enforce SPS -> PPS -> IRAP detection order to fix invalid stream detection

[xiongweixiao <xiongweixiaoxxw@gmail.com>]

The current vvc_probe function checks for SPS, PPS, and IRAP NAL units but does not enforce their detection order. This can lead to false positives when PPS or IRAP appear before SPS, causing malformed or non-compliant bitstreams to be incorrectly identified as valid VVC streams.

This patch modifies the logic to use boolean flags and enforces the correct detection sequence: SPS must be detected before PPS, and PPS before IRAP. This ensures more accurate probing and prevents invalid bitstreams from being misidentified.

This change addresses issues reported in:
- https://trac.ffmpeg.org/ticket/11496
- https://trac.ffmpeg.org/ticket/11087

Signed-off-by: xiongweixiao <xiongweixiaoxxw@gmail.com>
---
 libavformat/vvcdec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/vvcdec.c b/libavformat/vvcdec.c
index 0a0e24b71c..573b352f41 100644
--- a/libavformat/vvcdec.c
+++ b/libavformat/vvcdec.c
@@ -60,11 +60,11 @@ static int vvc_probe(const AVProbeData *p)
 
             switch (type) {
             case VVC_SPS_NUT:       sps++;  break;
-            case VVC_PPS_NUT:       pps++;  break;
+            case VVC_PPS_NUT:       if (sps) pps++;  break;
             case VVC_IDR_N_LP:
             case VVC_IDR_W_RADL:
             case VVC_CRA_NUT:
-            case VVC_GDR_NUT:       irap++; break;
+            case VVC_GDR_NUT:       if (pps) irap++; break;
             }
         }
     }
-- 
2.34.1

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