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Frame extractor: explain color accuracy issues

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This is only a javadoc change, setting expectations.

PiperOrigin-RevId: 702295210
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dancho 2024-12-03 04:54:04 -08:00 committed by Copybara-Service
parent e4993779db
commit 7821e7702b
1 changed files with 22 additions and 0 deletions
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libraries/transformer/src/main/java/androidx/media3/transformer/ExperimentalFrameExtractor.java
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@ -40,6 +40,8 @@ import android.opengl.GLES20;
import android.opengl.GLES30;
import android.os.Handler;
import android.os.Looper;
import android.view.SurfaceView;
import android.widget.ImageView;
import androidx.annotation.CallSuper;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
@ -63,6 +65,7 @@ import androidx.media3.effect.GlEffect;
import androidx.media3.effect.GlShaderProgram;
import androidx.media3.effect.MatrixTransformation;
import androidx.media3.effect.PassthroughShaderProgram;
import androidx.media3.effect.RgbMatrix;
import androidx.media3.effect.ScaleAndRotateTransformation;
import androidx.media3.exoplayer.DecoderCounters;
import androidx.media3.exoplayer.DecoderReuseEvaluation;
@ -96,6 +99,25 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
* <p>This class is experimental and will be renamed or removed in a future release.
*
* <p>Frame extractor instances must be accessed from a single application thread.
*
* <p>This class may produce incorrect or washed out colors, or images that have too high contrast
* for inputs not covered by <a
* href="https://cs.android.com/android/_/android/platform/cts/+/aaa242e5c26466cf245fa85ff8a7750378de9d72:tests/media/src/android/mediav2/cts/DecodeGlAccuracyTest.java;drc=d0d5ff338f8b84adf9066358bac435b1be3bbe61;l=534">testDecodeGlAccuracyRGB
* CTS test</a>. That is:
*
* <ul>
* <li>Inputs of BT.601 limited range are likely to produce accurate output with either
* {@linkplain MediaCodecSelector#PREFER_SOFTWARE software} or {@linkplain
* MediaCodecSelector#DEFAULT hardware} decoders across a wide range of devices.
* <li>Other inputs are likely to produce accurate output when using {@linkplain
* MediaCodecSelector#DEFAULT hardware} decoders on devices that are launched with API 13 or
* later.
* <li>HDR inputs will produce a {@link Bitmap} with {@link ColorSpace.Named#BT2020_HLG}. There
* are no guarantees that an HLG {@link Bitmap} displayed in {@link ImageView} and an HLG
* video displayed in {@link SurfaceView} will look the same.
* <li>Depending on the device and input video, color inaccuracies can be mitigated with an
* appropriate {@link RgbMatrix} effect.
* </ul>
*/
@UnstableApi
public final class ExperimentalFrameExtractor implements AnalyticsListener {