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Transformer GL: Fix rotation distortion by considering aspect ratio

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Compensate for aspect ratio of input frames, so that they're applied on
rectangular frames instead of square normalized-device-coordinate frames.

This fixes distortion most visible when rotating any GL video 45°
(non-rectangular frames) or 90° (stretched frames)

Tested by rotating several landscape/portrait demo videos.
(Automated tests will follow in <unknown commit>)

PiperOrigin-RevId: 419619743
This commit is contained in:
huangdarwin 2022-01-04 17:55:52 +00:00 committed by tonihei
parent f60dc148f8
commit 79f471b59a
1 changed files with 14 additions and 2 deletions
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16
libraries/transformer/src/main/java/androidx/media3/transformer/VideoSamplePipeline.java
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@ -60,12 +60,15 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
encoderOutputBuffer =
new DecoderInputBuffer(DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_DISABLED);
// Scale width and height to desired transformationRequest.outputHeight, preserving aspect
// ratio.
// TODO(internal b/209781577): Think about which edge length should be set for portrait videos.
float inputAspectRatio = (float) inputFormat.width / inputFormat.height;
int outputWidth = inputFormat.width;
int outputHeight = inputFormat.height;
if (transformationRequest.outputHeight != C.LENGTH_UNSET
&& transformationRequest.outputHeight != inputFormat.height) {
outputWidth = inputFormat.width * transformationRequest.outputHeight / inputFormat.height;
outputWidth = Math.round(inputAspectRatio * transformationRequest.outputHeight);
outputHeight = transformationRequest.outputHeight;
}
@ -79,10 +82,19 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
} else {
outputRotationDegrees = inputFormat.rotationDegrees;
}
if ((inputFormat.rotationDegrees % 180) != 0) {
inputAspectRatio = 1.0f / inputAspectRatio;
}
// Scale frames by input aspect ratio, to account for FrameEditor normalized device coordinates
// (-1 to 1) and preserve frame relative dimensions during transformations (ex. rotations).
transformationRequest.transformationMatrix.preScale(inputAspectRatio, 1);
transformationRequest.transformationMatrix.postScale(1.0f / inputAspectRatio, 1);
// The decoder rotates videos to their intended display orientation. The frameEditor rotates
// them back for improved encoder compatibility.
// TODO(b/201293185): After fragment shader transformations are implemented, put
// postrotation in a later vertex shader.
// postRotate in a later vertex shader.
transformationRequest.transformationMatrix.postRotate(outputRotationDegrees);
encoder =