Commit fd9a8f25a0 for ffmpeg

commit fd9a8f25a07bbec3e6b25339177ef1e2d49cbf05
Author: dhalsimax <29256273+dhalsimax@users.noreply.github.com>
Date:   Thu Oct 1 08:38:55 2026 +0200

    avfilter/vf_tonemap_opencl: zero the peak detection buffer

    The kernel keeps its peak detection state in util_mem (frame index,
    frame count, running totals of peak and average) and expects it to
    start at zero. The buffer is created without a host pointer, so per the
    OpenCL spec its contents are undefined. Intel's compute-runtime (NEO
    24.35, legacy branch, on a Gen9 Apollo Lake) hands out recycled memory,
    and the totals can start as garbage: the detected peak is then huge and
    the whole stream comes out black (Y=16), or with the wrong brightness.
    The same command gave black video every time on one film and a correct
    picture on another; with the buffer zeroed both are correct.

    Create the buffer from a zeroed array with CL_MEM_COPY_HOST_PTR.

    Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
    Claude-Session: https://claude.ai/code/session_01VB8Q6zwZGmj1CET8B15HLg

diff --git a/libavfilter/vf_tonemap_opencl.c b/libavfilter/vf_tonemap_opencl.c
index 2f47cfd49f..aa8f50b6d6 100644
--- a/libavfilter/vf_tonemap_opencl.c
+++ b/libavfilter/vf_tonemap_opencl.c
@@ -116,6 +116,7 @@ static const float sdr_avg = 0.25f;

 static int tonemap_opencl_init(AVFilterContext *avctx)
 {
+    unsigned util_init[2 * DETECTION_FRAMES + 7] = { 0 };
     TonemapOpenCLContext *ctx = avctx->priv;
     int rgb2rgb_passthrough = 1;
     double rgb2rgb[3][3], rgb2yuv[3][3], yuv2rgb[3][3];
@@ -258,10 +259,12 @@ static int tonemap_opencl_init(AVFilterContext *avctx)
     ctx->kernel = clCreateKernel(ctx->ocf.program, "tonemap", &cle);
     CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create kernel %d.\n", cle);

+    // The kernel keeps its peak detection state here and expects it to
+    // start at zero, but a buffer created without a host pointer has
+    // undefined contents.
     ctx->util_mem =
-        clCreateBuffer(ctx->ocf.hwctx->context, 0,
-                       (2 * DETECTION_FRAMES + 7) * sizeof(unsigned),
-                       NULL, &cle);
+        clCreateBuffer(ctx->ocf.hwctx->context, CL_MEM_COPY_HOST_PTR,
+                       sizeof(util_init), util_init, &cle);
     CL_FAIL_ON_ERROR(AVERROR(EIO), "Failed to create util buffer: %d.\n", cle);

     ctx->initialised = 1;