From 153740386a1a3b71d00742b654b9af3dafd24ba3 Mon Sep 17 00:00:00 2001
From: huangdarwin <huangdarwin@google.com>
Date: Mon, 21 Aug 2023 11:53:22 +0100
Subject: [PATCH] Compositor: Use lists for inputs instead of instances.

This makes the code a bit more flexible for when we allow for an arbitrary
number of inputs.

PiperOrigin-RevId: 558740536
---
 .../media3/effect/DefaultVideoCompositor.java | 36 +++++++++++--------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/libraries/effect/src/main/java/androidx/media3/effect/DefaultVideoCompositor.java b/libraries/effect/src/main/java/androidx/media3/effect/DefaultVideoCompositor.java
index 2d92a34f56..3755c08468 100644
--- a/libraries/effect/src/main/java/androidx/media3/effect/DefaultVideoCompositor.java
+++ b/libraries/effect/src/main/java/androidx/media3/effect/DefaultVideoCompositor.java
@@ -271,18 +271,22 @@ public final class DefaultVideoCompositor implements VideoCompositor {
 
     // TODO: b/262694346 -
     //  * Support an arbitrary number of inputs.
-    //  * Allow different frame dimensions.
-    InputFrameInfo inputFrame1 = framesToComposite.get(0);
-    InputFrameInfo inputFrame2 = framesToComposite.get(1);
-    checkState(inputFrame1.texture.width == inputFrame2.texture.width);
-    checkState(inputFrame1.texture.height == inputFrame2.texture.height);
+    //  * Allow different input frame dimensions.
+    InputFrameInfo primaryInputFrame = framesToComposite.get(PRIMARY_INPUT_ID);
+    GlTextureInfo primaryInputTexture = primaryInputFrame.texture;
     outputTexturePool.ensureConfigured(
-        glObjectsProvider, inputFrame1.texture.width, inputFrame1.texture.height);
+        glObjectsProvider, primaryInputTexture.width, primaryInputTexture.height);
+
+    for (int i = 1; i < framesToComposite.size(); i++) {
+      GlTextureInfo textureToComposite = framesToComposite.get(i).texture;
+      checkState(primaryInputTexture.width == textureToComposite.width);
+      checkState(primaryInputTexture.height == textureToComposite.height);
+    }
     GlTextureInfo outputTexture = outputTexturePool.useTexture();
-    long outputPresentationTimestampUs = framesToComposite.get(PRIMARY_INPUT_ID).presentationTimeUs;
+    long outputPresentationTimestampUs = primaryInputFrame.presentationTimeUs;
     outputTextureTimestamps.add(outputPresentationTimestampUs);
 
-    drawFrame(inputFrame1.texture, inputFrame2.texture, outputTexture);
+    drawFrame(framesToComposite, outputTexture);
     long syncObject = GlUtil.createGlSyncFence();
     syncObjects.add(syncObject);
     textureOutputListener.onTextureRendered(
@@ -295,7 +299,7 @@ public final class DefaultVideoCompositor implements VideoCompositor {
     releaseFrames(primaryInputSource, /* numberOfFramesToRelease= */ 1);
     releaseExcessFramesInAllSecondaryStreams();
 
-    if (allInputsEnded && inputSources.get(PRIMARY_INPUT_ID).frameInfos.isEmpty()) {
+    if (allInputsEnded && primaryInputSource.frameInfos.isEmpty()) {
       listener.onEnded();
     }
   }
@@ -397,8 +401,7 @@ public final class DefaultVideoCompositor implements VideoCompositor {
     }
   }
 
-  private void drawFrame(
-      GlTextureInfo inputTexture1, GlTextureInfo inputTexture2, GlTextureInfo outputTexture)
+  private void drawFrame(List<InputFrameInfo> framesToComposite, GlTextureInfo outputTexture)
       throws GlUtil.GlException {
     GlUtil.focusFramebufferUsingCurrentContext(
         outputTexture.fboId, outputTexture.width, outputTexture.height);
@@ -420,8 +423,9 @@ public final class DefaultVideoCompositor implements VideoCompositor {
     GlUtil.checkGlError();
 
     // Draw textures from back to front.
-    blendOntoFocusedTexture(inputTexture2.texId);
-    blendOntoFocusedTexture(inputTexture1.texId);
+    for (int i = framesToComposite.size() - 1; i >= 0; i--) {
+      blendOntoFocusedTexture(framesToComposite.get(i).texture.texId);
+    }
 
     GLES20.glDisable(GLES20.GL_BLEND);
 
@@ -459,8 +463,10 @@ public final class DefaultVideoCompositor implements VideoCompositor {
 
   /** Holds information on an input source. */
   private static final class InputSource {
-    // A queue of {link InputFrameInfo}s, inserted in order from lower to higher {@code
-    // presentationTimeUs} values.
+    /**
+     * A queue of {link InputFrameInfo}s, monotonically increasing in order of {@code
+     * presentationTimeUs} values.
+     */
     public final Queue<InputFrameInfo> frameInfos;
 
     public boolean isInputEnded;