Added codec-aware encoding profiles and moved pixel format to per-variant output.

Encoders now receive the codec being used, allowing them to adjust their flags accordingly. For example, the software encoder gates x264-specific parameters behind a codec check so that future encoders like libx265 or libsvtav1 can provide their own flags without conflict. Pixel format is now specified per variant with a stream specifier rather than globally, enabling codecs like AV1 to use 10-bit color for improved compression efficiency while H.264 variants continue using yuv420p.

core/transcoder/encoder_qsv.go

@@ -20,22 +20,18 @@ func (e *QuicksyncEncoder) GlobalFlags() []string {
 	}
 }
 
-func (e *QuicksyncEncoder) PixelFormat() string {
-	return "qsv"
-}
-
-func (e *QuicksyncEncoder) Scaler() string {
-	return "scale_qsv"
-}
-
-func (e *QuicksyncEncoder) ExtraFilters() string {
-	return "hwupload=extra_hw_frames=64,format=qsv"
-}
-
 func (e *QuicksyncEncoder) ExtraArguments() []string {
 	return nil
 }
 
+func (e *QuicksyncEncoder) ProfileForCodec(codec string) CodecProfile {
+	return CodecProfile{
+		PixelFormat:  "qsv",
+		Scaler:       "scale_qsv",
+		ExtraFilters: "hwupload=extra_hw_frames=64,format=qsv",
+	}
+}
+
 func (e *QuicksyncEncoder) VariantFlags(v *HLSVariant) []string {
 	return nil
 }