[FFmpeg-cvslog] avcodec/osq: Switch back to av_ceil_log2()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Tue Jun 17 02:31:28 2025 +0200| [a5f861d335491ce2350102b74c7a17f875cad0ed] | committer: Michael Niedermayer

avcodec/osq: Switch back to av_ceil_log2()

This returns to code closer to prior 56c334d732dbbce43b0c8fc0809ec545b7946832
The prior fixes should limit the sum and avoid the need for double argument log2()

Fixes: Assertion n>=0 && n<=32 failed at libavcodec/get_bits.h:406
Fixes: 410109093/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_OSQ_fuzzer-6550900028276736

No testcases except fuzzers

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a5f861d335491ce2350102b74c7a17f875cad0ed
---

 libavcodec/osq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/osq.c b/libavcodec/osq.c
index d3b1d86ee3..025be667a3 100644
--- a/libavcodec/osq.c
+++ b/libavcodec/osq.c
@@ -165,7 +165,8 @@ static int update_residue_parameter(OSQChannel *cb)
     if (!sum)
         return 0;
     x = sum / cb->count;
-    rice_k = ceil(log2(x));
+    av_assert2(x <= 0x80000000U);
+    rice_k = av_ceil_log2(x);
     if (rice_k >= 30) {
         double f = floor(sum / 1.4426952 + 0.5);
         if (f <= 1) {