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Rename expected to reference in SsimHelper.

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Reference is clearer when used in conjunction with actual, and matches
other SSIM documentation.

PiperOrigin-RevId: 449486177
This commit is contained in:
samrobinson 2022-05-18 16:15:24 +01:00 committed by Ian Baker
parent c78c1f5891
commit 2a45dd3930
1 changed files with 20 additions and 20 deletions
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40
libraries/transformer/src/androidTest/java/androidx/media3/transformer/SsimHelper.java
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@ -63,44 +63,44 @@ public final class SsimHelper {
private static final int DECODED_IMAGE_CHANNEL_COUNT = 3;
/**
* Returns the mean SSIM score between the expected and the actual video.
* Returns the mean SSIM score between the reference and the actual video.
*
* <p>The method compares every {@link #DEFAULT_COMPARISON_INTERVAL n-th} frame from both videos.
*
* @param context The {@link Context}.
* @param expectedVideoPath The path to the expected video file, must be in {@link
* @param referenceVideoPath The path to the reference video file, must be in {@link
* Context#getAssets() Assets}.
* @param actualVideoPath The path to the actual video file.
* @throws IOException When unable to open the provided video paths.
*/
public static double calculate(Context context, String expectedVideoPath, String actualVideoPath)
public static double calculate(Context context, String referenceVideoPath, String actualVideoPath)
throws IOException, InterruptedException {
VideoDecodingWrapper expectedDecodingWrapper =
new VideoDecodingWrapper(context, expectedVideoPath, DEFAULT_COMPARISON_INTERVAL);
VideoDecodingWrapper referenceDecodingWrapper =
new VideoDecodingWrapper(context, referenceVideoPath, DEFAULT_COMPARISON_INTERVAL);
VideoDecodingWrapper actualDecodingWrapper =
new VideoDecodingWrapper(context, actualVideoPath, DEFAULT_COMPARISON_INTERVAL);
@Nullable byte[] expectedLumaBuffer = null;
@Nullable byte[] referenceLumaBuffer = null;
@Nullable byte[] actualLumaBuffer = null;
double accumulatedSsim = 0.0;
int comparedImagesCount = 0;
try {
while (true) {
@Nullable Image expectedImage = expectedDecodingWrapper.runUntilComparisonFrameOrEnded();
@Nullable Image referenceImage = referenceDecodingWrapper.runUntilComparisonFrameOrEnded();
@Nullable Image actualImage = actualDecodingWrapper.runUntilComparisonFrameOrEnded();
if (expectedImage == null) {
if (referenceImage == null) {
assertThat(actualImage).isNull();
break;
}
checkNotNull(actualImage);
int width = expectedImage.getWidth();
int height = expectedImage.getHeight();
int width = referenceImage.getWidth();
int height = referenceImage.getHeight();
assertThat(actualImage.getWidth()).isEqualTo(width);
assertThat(actualImage.getHeight()).isEqualTo(height);
if (expectedLumaBuffer == null || expectedLumaBuffer.length != width * height) {
expectedLumaBuffer = new byte[width * height];
if (referenceLumaBuffer == null || referenceLumaBuffer.length != width * height) {
referenceLumaBuffer = new byte[width * height];
}
if (actualLumaBuffer == null || actualLumaBuffer.length != width * height) {
actualLumaBuffer = new byte[width * height];
@ -108,20 +108,20 @@ public final class SsimHelper {
try {
accumulatedSsim +=
SsimCalculator.calculate(
extractLumaChannelBuffer(expectedImage, expectedLumaBuffer),
extractLumaChannelBuffer(referenceImage, referenceLumaBuffer),
extractLumaChannelBuffer(actualImage, actualLumaBuffer),
/* offset= */ 0,
/* stride= */ width,
width,
height);
} finally {
expectedImage.close();
referenceImage.close();
actualImage.close();
}
comparedImagesCount++;
}
} finally {
expectedDecodingWrapper.close();
referenceDecodingWrapper.close();
actualDecodingWrapper.close();
}
assertWithMessage("Input had no frames.").that(comparedImagesCount).isGreaterThan(0);
@ -347,7 +347,7 @@ public final class SsimHelper {
/**
* Calculates the Structural Similarity Index (SSIM) between two images.
*
* @param expected The luma channel (Y) bitmap of the expected image.
* @param reference The luma channel (Y) bitmap of the reference image.
* @param actual The luma channel (Y) bitmap of the actual image.
* @param offset The offset.
* @param stride The stride of the bitmap.
@ -356,23 +356,23 @@ public final class SsimHelper {
* @return The SSIM score between the input images.
*/
public static double calculate(
byte[] expected, byte[] actual, int offset, int stride, int width, int height) {
byte[] reference, byte[] actual, int offset, int stride, int width, int height) {
double totalSsim = 0;
int windowsCount = 0;
// X refers to the expected image, while Y refers to the actual image.
// X refers to the reference image, while Y refers to the actual image.
for (int currentWindowY = 0; currentWindowY < height; currentWindowY += WINDOW_SIZE) {
int windowHeight = computeWindowSize(currentWindowY, height);
for (int currentWindowX = 0; currentWindowX < width; currentWindowX += WINDOW_SIZE) {
windowsCount++;
int windowWidth = computeWindowSize(currentWindowX, width);
int start = getGlobalCoordinate(currentWindowX, currentWindowY, stride, offset);
double meanX = getMean(expected, start, stride, windowWidth, windowHeight);
double meanX = getMean(reference, start, stride, windowWidth, windowHeight);
double meanY = getMean(actual, start, stride, windowWidth, windowHeight);
double[] variances =
getVariancesAndCovariance(
expected, actual, meanX, meanY, start, stride, windowWidth, windowHeight);
reference, actual, meanX, meanY, start, stride, windowWidth, windowHeight);
// varX is the variance of window X, covXY is the covariance between window X and Y.
double varX = variances[0];
double varY = variances[1];