/*
* Copyright 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.media3.effect;
import static androidx.media3.common.util.Assertions.checkState;
import android.content.Context;
import androidx.media3.common.FrameProcessingException;
import androidx.media3.common.util.UnstableApi;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
/** Provides common color filters. */
@UnstableApi
public class RgbFilter implements RgbMatrix {
private static final int COLOR_FILTER_GRAYSCALE_INDEX = 1;
private static final int COLOR_FILTER_INVERTED_INDEX = 2;
// Grayscale transformation matrix using the BT.709 luminance coefficients from
// https://en.wikipedia.org/wiki/Grayscale#Converting_colour_to_grayscale
private static final float[] FILTER_MATRIX_GRAYSCALE_SDR = {
0.2126f, 0.2126f, 0.2126f, 0, 0.7152f, 0.7152f, 0.7152f, 0, 0.0722f, 0.0722f, 0.0722f, 0, 0, 0,
0, 1
};
// Grayscale transformation using the BT.2020 primary colors from
// https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.2020-2-201510-I!!PDF-E.pdf
// TODO(b/241240659): Add HDR tests once infrastructure supports it.
private static final float[] FILTER_MATRIX_GRAYSCALE_HDR = {
0.2627f, 0.2627f, 0.2627f, 0, 0.6780f, 0.6780f, 0.6780f, 0, 0.0593f, 0.0593f, 0.0593f, 0, 0, 0,
0, 1
};
// Inverted filter uses the transformation R' = -R + 1 = 1 - R.
private static final float[] FILTER_MATRIX_INVERTED = {
-1, 0, 0, 0, 0, -1, 0, 0, 0, 0, -1, 0, 1, 1, 1, 1
};
private final int colorFilter;
/**
* Ensures that the usage of HDR is consistent. {@code null} indicates that HDR has not yet been
* set.
*/
private @MonotonicNonNull Boolean useHdr;
/** Creates a new grayscale {@code RgbFilter} instance. */
public static RgbFilter createGrayscaleFilter() {
return new RgbFilter(COLOR_FILTER_GRAYSCALE_INDEX);
}
/** Creates a new inverted {@code RgbFilter} instance. */
public static RgbFilter createInvertedFilter() {
return new RgbFilter(COLOR_FILTER_INVERTED_INDEX);
}
private RgbFilter(int colorFilter) {
this.colorFilter = colorFilter;
}
private void checkForConsistentHdrSetting(boolean useHdr) {
if (this.useHdr == null) {
this.useHdr = useHdr;
} else {
checkState(this.useHdr == useHdr, "Changing HDR setting is not supported.");
}
}
@Override
public float[] getMatrix(long presentationTimeUs, boolean useHdr) {
checkForConsistentHdrSetting(useHdr);
switch (colorFilter) {
case COLOR_FILTER_GRAYSCALE_INDEX:
return useHdr ? FILTER_MATRIX_GRAYSCALE_HDR : FILTER_MATRIX_GRAYSCALE_SDR;
case COLOR_FILTER_INVERTED_INDEX:
return FILTER_MATRIX_INVERTED;
default:
// Should never happen.
throw new IllegalStateException("Invalid color filter " + colorFilter);
}
}
@Override
public SingleFrameGlTextureProcessor toGlTextureProcessor(Context context, boolean useHdr)
throws FrameProcessingException {
checkForConsistentHdrSetting(useHdr);
return RgbMatrix.super.toGlTextureProcessor(context, useHdr);
}
}