Transformer GL: Add setResolution() API.

Simple, initial implementation to allow setResolution()
to set the output height, for downscaling/upscaling.

Per TODOs, follow-up CLs may change layering, add UI,
or allow querying decoders for more resolution options.

PiperOrigin-RevId: 410203343

libraries/transformer/src/main/java/androidx/media3/transformer/OpenGlFrameEditor.java

@@ -29,21 +29,32 @@
 import android.opengl.GLES20;
 import android.view.Surface;
 import androidx.annotation.RequiresApi;
-import androidx.media3.common.Format;
 import androidx.media3.common.util.GlUtil;
 import java.io.IOException;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
-/** Applies OpenGL transformations to video frames. */
+/**
+ * OpenGlFrameEditor applies changes to individual video frames using OpenGL. Changes include just
+ * resolution for now, but may later include brightness, cropping, rotation, etc.
+ */
 @RequiresApi(18)
 /* package */ final class OpenGlFrameEditor {
 
   static {
     GlUtil.glAssertionsEnabled = true;
   }
 
+  /**
+   * Returns a new OpenGlFrameEditor for applying changes to individual frames.
+   *
+   * @param context A {@link Context}.
+   * @param outputWidth The output width in pixels.
+   * @param outputHeight The output height in pixels.
+   * @param outputSurface The {@link Surface}.
+   * @return A configured OpenGlFrameEditor.
+   */
   public static OpenGlFrameEditor create(
-      Context context, Format inputFormat, Surface outputSurface) {
+      Context context, int outputWidth, int outputHeight, Surface outputSurface) {
     EGLDisplay eglDisplay = GlUtil.createEglDisplay();
     EGLContext eglContext;
     try {
@@ -52,7 +63,7 @@ public static OpenGlFrameEditor create(
       throw new IllegalStateException("EGL version is unsupported", e);
     }
     EGLSurface eglSurface = GlUtil.getEglSurface(eglDisplay, outputSurface);
-    GlUtil.focusSurface(eglDisplay, eglContext, eglSurface, inputFormat.width, inputFormat.height);
+    GlUtil.focusSurface(eglDisplay, eglContext, eglSurface, outputWidth, outputHeight);
     int textureId = GlUtil.createExternalTexture();
     GlUtil.Program copyProgram;
     try {

libraries/transformer/src/main/java/androidx/media3/transformer/TranscodingTransformer.java

@@ -71,9 +71,6 @@
  * <p>Temporary copy of the {@link Transformer} class, which transforms by transcoding rather than
  * by muxing. This class is intended to replace the Transformer class.
  *
- * <p>TODO(http://b/202131097): Replace the Transformer class with TranscodingTransformer, and
- * rename this class to Transformer.
- *
  * <p>The same TranscodingTransformer instance can be used to transform multiple inputs
  * (sequentially, not concurrently).
  *
@@ -89,16 +86,22 @@
 @RequiresApi(18)
 @UnstableApi
 public final class TranscodingTransformer {
+  // TODO(http://b/202131097): Replace the Transformer class with TranscodingTransformer, and
+  // rename this class to Transformer.
 
   /** A builder for {@link TranscodingTransformer} instances. */
   public static final class Builder {
 
+    // Mandatory field.
     private @MonotonicNonNull Context context;
+
+    // Optional fields.
     private @MonotonicNonNull MediaSourceFactory mediaSourceFactory;
     private Muxer.Factory muxerFactory;
     private boolean removeAudio;
     private boolean removeVideo;
     private boolean flattenForSlowMotion;
+    private int outputHeight;
     private String outputMimeType;
     @Nullable private String audioMimeType;
     @Nullable private String videoMimeType;
@@ -109,6 +112,7 @@ public static final class Builder {
     /** Creates a builder with default values. */
     public Builder() {
       muxerFactory = new FrameworkMuxer.Factory();
+      outputHeight = Transformation.NO_VALUE;
       outputMimeType = MimeTypes.VIDEO_MP4;
       listener = new Listener() {};
       looper = Util.getCurrentOrMainLooper();
@@ -123,6 +127,7 @@ private Builder(TranscodingTransformer transcodingTransformer) {
       this.removeAudio = transcodingTransformer.transformation.removeAudio;
       this.removeVideo = transcodingTransformer.transformation.removeVideo;
       this.flattenForSlowMotion = transcodingTransformer.transformation.flattenForSlowMotion;
+      this.outputHeight = transcodingTransformer.transformation.outputHeight;
       this.outputMimeType = transcodingTransformer.transformation.outputMimeType;
       this.audioMimeType = transcodingTransformer.transformation.audioMimeType;
       this.videoMimeType = transcodingTransformer.transformation.videoMimeType;
@@ -215,6 +220,37 @@ public Builder setFlattenForSlowMotion(boolean flattenForSlowMotion) {
       return this;
     }
 
+    /**
+     * Sets the output resolution using the output height. The default value is {@link
+     * Transformation#NO_VALUE}, which will use the same height as the input. Output width will
+     * scale to preserve the input video's aspect ratio.
+     *
+     * <p>For now, only "popular" heights like 240, 360, 480, 720, 1080, 1440, or 2160 are
+     * supported, to ensure compatibility on different devices.
+     *
+     * <p>For example, a 1920x1440 video can be scaled to 640x480 by calling setResolution(480).
+     *
+     * @param outputHeight The output height in pixels.
+     * @return This builder.
+     */
+    public Builder setResolution(int outputHeight) {
+      // TODO(Internal b/201293185): Restructure to input a Presentation class.
+      // TODO(Internal b/201293185): Check encoder codec capabilities in order to allow arbitrary
+      // resolutions and reasonable fallbacks.
+      if (outputHeight != 240
+          && outputHeight != 360
+          && outputHeight != 480
+          && outputHeight != 720
+          && outputHeight != 1080
+          && outputHeight != 1440
+          && outputHeight != 2160) {
+        throw new IllegalArgumentException(
+            "Please use a height of 240, 360, 480, 720, 1080, 1440, or 2160.");
+      }
+      this.outputHeight = outputHeight;
+      return this;
+    }
+
     /**
      * Sets the MIME type of the output. The default value is {@link MimeTypes#VIDEO_MP4}. Supported
      * values are:
@@ -369,6 +405,7 @@ public TranscodingTransformer build() {
               removeAudio,
               removeVideo,
               flattenForSlowMotion,
+              outputHeight,
               outputMimeType,
               audioMimeType,
               videoMimeType);

libraries/transformer/src/main/java/androidx/media3/transformer/Transformation.java

@@ -21,9 +21,13 @@
 /** A media transformation configuration. */
 /* package */ final class Transformation {
 
+  /** A value for various fields to indicate that the field's value is unknown or not set. */
+  public static final int NO_VALUE = -1;
+
   public final boolean removeAudio;
   public final boolean removeVideo;
   public final boolean flattenForSlowMotion;
+  public final int outputHeight;
   public final String outputMimeType;
   @Nullable public final String audioMimeType;
   @Nullable public final String videoMimeType;
@@ -32,12 +36,14 @@ public Transformation(
       boolean removeAudio,
       boolean removeVideo,
       boolean flattenForSlowMotion,
+      int outputHeight,
       String outputMimeType,
       @Nullable String audioMimeType,
       @Nullable String videoMimeType) {
     this.removeAudio = removeAudio;
     this.removeVideo = removeVideo;
     this.flattenForSlowMotion = flattenForSlowMotion;
+    this.outputHeight = outputHeight;
     this.outputMimeType = outputMimeType;
     this.audioMimeType = audioMimeType;
     this.videoMimeType = videoMimeType;

libraries/transformer/src/main/java/androidx/media3/transformer/Transformer.java

@@ -304,6 +304,7 @@ public Transformer build() {
               removeAudio,
               removeVideo,
               flattenForSlowMotion,
+              /* outputHeight= */ Transformation.NO_VALUE,
               outputMimeType,
               /* audioMimeType= */ null,
               /* videoMimeType= */ null);

libraries/transformer/src/main/java/androidx/media3/transformer/TransformerTranscodingVideoRenderer.java

@@ -83,7 +83,7 @@ public void render(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackEx
     while (feedMuxerFromPipeline() || samplePipeline.processData() || feedPipelineFromInput()) {}
   }
 
-  /** Attempts to read the input format and to initialize the sample pipeline. */
+  /** Attempts to read the input format and to initialize the sample or passthrough pipeline. */
   @EnsuresNonNullIf(expression = "samplePipeline", result = true)
   private boolean ensureRendererConfigured() throws ExoPlaybackException {
     if (samplePipeline != null) {
@@ -96,8 +96,10 @@ private boolean ensureRendererConfigured() throws ExoPlaybackException {
       return false;
     }
     Format decoderInputFormat = checkNotNull(formatHolder.format);
-    if (transformation.videoMimeType != null
-        && !transformation.videoMimeType.equals(decoderInputFormat.sampleMimeType)) {
+    if ((transformation.videoMimeType != null
+            && !transformation.videoMimeType.equals(decoderInputFormat.sampleMimeType))
+        || (transformation.outputHeight != Transformation.NO_VALUE
+            && transformation.outputHeight != decoderInputFormat.height)) {
       samplePipeline =
           new VideoSamplePipeline(context, decoderInputFormat, transformation, getIndex());
     } else {

libraries/transformer/src/main/java/androidx/media3/transformer/VideoSamplePipeline.java

@@ -57,12 +57,22 @@ public VideoSamplePipeline(
 
     encoderOutputBuffer =
         new DecoderInputBuffer(DecoderInputBuffer.BUFFER_REPLACEMENT_MODE_DISABLED);
+
+    int outputWidth = decoderInputFormat.width;
+    int outputHeight = decoderInputFormat.height;
+    if (transformation.outputHeight != Transformation.NO_VALUE
+        && transformation.outputHeight != decoderInputFormat.height) {
+      outputWidth =
+          decoderInputFormat.width * transformation.outputHeight / decoderInputFormat.height;
+      outputHeight = transformation.outputHeight;
+    }
+
     try {
       encoder =
           MediaCodecAdapterWrapper.createForVideoEncoding(
               new Format.Builder()
-                  .setWidth(decoderInputFormat.width)
-                  .setHeight(decoderInputFormat.height)
+                  .setWidth(outputWidth)
+                  .setHeight(outputHeight)
                   .setSampleMimeType(
                       transformation.videoMimeType != null
                           ? transformation.videoMimeType
@@ -77,7 +87,8 @@ public VideoSamplePipeline(
     openGlFrameEditor =
         OpenGlFrameEditor.create(
             context,
-            decoderInputFormat,
+            outputWidth,
+            outputHeight,
             /* outputSurface= */ checkNotNull(encoder.getInputSurface()));
     try {
       decoder =