[FFmpeg-cvslog] avcodec/libx264: Add the SSE computation for libx264.

[Elias Carotti]

ffmpeg | branch: master | Elias Carotti <eliascrt _at_ amazon _dot_ .it> | Fri Sep 15 20:05:43 2023 +0200| [644b2235c5bb1e3ee89a92180d87796ec4c18ec8] | committer: Anton Khirnov

avcodec/libx264: Add the SSE computation for libx264.

Since libx264 only provides a per-frame per-channel PSNR, this is
inverted to get back the SSE.

Signed-off-by: Anton Khirnov <anton at khirnov.net>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=644b2235c5bb1e3ee89a92180d87796ec4c18ec8
---

 libavcodec/libx264.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
index 77a9f173b4..182e20f622 100644
--- a/libavcodec/libx264.c
+++ b/libavcodec/libx264.c
@@ -726,7 +726,36 @@ FF_ENABLE_DEPRECATION_WARNINGS
 
     pkt->flags |= AV_PKT_FLAG_KEY*pic_out.b_keyframe;
     if (ret) {
-        ff_side_data_set_encoder_stats(pkt, (pic_out.i_qpplus1 - 1) * FF_QP2LAMBDA, NULL, 0, pict_type);
+        int error_count = 0;
+        int64_t *errors = NULL;
+        int64_t sse[3] = {0};
+
+        if (ctx->flags & AV_CODEC_FLAG_PSNR) {
+            const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(ctx->pix_fmt);
+            double scale[3] = { 1,
+                (double)(1 << pix_desc->log2_chroma_h) * (1 << pix_desc->log2_chroma_w),
+                (double)(1 << pix_desc->log2_chroma_h) * (1 << pix_desc->log2_chroma_w),
+            };
+
+            error_count = pix_desc->nb_components;
+
+            for (int i = 0; i < pix_desc->nb_components; ++i) {
+                double max_value = (double)(1 << pix_desc->comp[i].depth) - 1.0;
+                double plane_size = ctx->width * (double)ctx->height / scale[i];
+
+                /* psnr = 10 * log10(max_value * max_value / mse) */
+                double mse = (max_value * max_value) / pow(10, pic_out.prop.f_psnr[i] / 10.0);
+
+                /* SSE = MSE * width * height / scale -> because of possible chroma downsampling */
+                sse[i] = (int64_t)floor(mse * plane_size + .5);
+            };
+
+            errors = sse;
+        }
+
+        ff_side_data_set_encoder_stats(pkt, (pic_out.i_qpplus1 - 1) * FF_QP2LAMBDA,
+                                       errors, error_count, pict_type);
+
         if (wallclock)
             ff_side_data_set_prft(pkt, wallclock);
     }