SeparableConvolution.java
/*
* Copyright 2023 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 android.content.Context;
import androidx.annotation.RequiresApi;
import androidx.media3.common.VideoFrameProcessingException;
import androidx.media3.common.util.UnstableApi;
/**
* A {@link GlEffect} for performing separable convolutions.
*
* <p>A single 1D convolution function is applied horizontally on a first pass and vertically on a
* second pass.
*/
@UnstableApi
@RequiresApi(26) // See SeparableConvolutionShaderProgram.
public abstract class SeparableConvolution implements GlEffect {
private final float scaleWidth;
private final float scaleHeight;
/** Creates an instance with {@code scaleWidth} and {@code scaleHeight} set to {@code 1.0f}. */
public SeparableConvolution() {
this(/* scaleWidth= */ 1.0f, /* scaleHeight= */ 1.0f);
}
/**
* Creates an instance.
*
* @param scaleWidth The scaling factor used to determine the width of the output relative to the
* input.
* @param scaleHeight The scaling factor used to determine the height of the output relative to
* the input.
*/
public SeparableConvolution(float scaleWidth, float scaleHeight) {
this.scaleWidth = scaleWidth;
this.scaleHeight = scaleHeight;
}
/**
* Returns a {@linkplain ConvolutionFunction1D 1D convolution function}.
*
* @param presentationTimeUs The presentation timestamp of the input frame, in microseconds.
*/
public abstract ConvolutionFunction1D getConvolution(long presentationTimeUs);
@Override
public GlShaderProgram toGlShaderProgram(Context context, boolean useHdr)
throws VideoFrameProcessingException {
return new SeparableConvolutionShaderProgram(
context, useHdr, /* convolution= */ this, scaleWidth, scaleHeight);
}
}