Update transcode_bench.py

transcode_bench.py

@@ -357,9 +357,19 @@ class TranscodeJob:
             if 'vaapi' in self.encoder and not self.hw_decode:
                 cmd.extend(['-vf', 'format=nv12,hwupload'])
 
+            # Build encoding parameters
+            encode_params = ['-c:v', self.encoder]
+
+            # For VA-API, use CQP mode instead of bitrate if needed
+            if 'vaapi' in self.encoder:
+                # Use constant quality mode (lower is better quality, 20-30 is good)
+                encode_params.extend(['-qp', '23'])
+            else:
+                # Use bitrate mode for other encoders
+                encode_params.extend(['-b:v', '4M'])
+
+            cmd.extend(encode_params)
             cmd.extend([
-                '-c:v', self.encoder,
-                '-b:v', '4M',
                 '-c:a', 'aac',
                 '-b:a', '128k',
                 '-f', 'null' if os.name != 'nt' else 'null',