sdk/android/api/org/webrtc/VideoFrame.java

/*
 *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.webrtc;

import android.graphics.Matrix;
import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.support.annotation.Nullable;
import java.nio.ByteBuffer;

/**
 * Java version of webrtc::VideoFrame and webrtc::VideoFrameBuffer. A difference from the C++
 * version is that no explicit tag is used, and clients are expected to use 'instanceof' to find the
 * right subclass of the buffer. This allows clients to create custom VideoFrame.Buffer in
 * arbitrary format in their custom VideoSources, and then cast it back to the correct subclass in
 * their custom VideoSinks. All implementations must also implement the toI420() function,
 * converting from the underlying representation if necessary. I420 is the most widely accepted
 * format and serves as a fallback for video sinks that can only handle I420, e.g. the internal
 * WebRTC software encoders.
 */
public class VideoFrame implements RefCounted {
  /**
   * Implements image storage medium. Might be for example an OpenGL texture or a memory region
   * containing I420-data.
   *
   * <p>Reference counting is needed since a video buffer can be shared between multiple VideoSinks,
   * and the buffer needs to be returned to the VideoSource as soon as all references are gone.
   */
  public interface Buffer extends RefCounted {
    /**
     * Resolution of the buffer in pixels.
     */
    @CalledByNative("Buffer") int getWidth();
    @CalledByNative("Buffer") int getHeight();

    /**
     * Returns a memory-backed frame in I420 format. If the pixel data is in another format, a
     * conversion will take place. All implementations must provide a fallback to I420 for
     * compatibility with e.g. the internal WebRTC software encoders.
     */
    @CalledByNative("Buffer") I420Buffer toI420();

    @Override @CalledByNative("Buffer") void retain();
    @Override @CalledByNative("Buffer") void release();

    /**
     * Crops a region defined by |cropx|, |cropY|, |cropWidth| and |cropHeight|. Scales it to size
     * |scaleWidth| x |scaleHeight|.
     */
    @CalledByNative("Buffer")
    Buffer cropAndScale(
        int cropX, int cropY, int cropWidth, int cropHeight, int scaleWidth, int scaleHeight);
  }

  /**
   * Interface for I420 buffers.
   */
  public interface I420Buffer extends Buffer {
    /**
     * Returns a direct ByteBuffer containing Y-plane data. The buffer capacity is at least
     * getStrideY() * getHeight() bytes. The position of the returned buffer is ignored and must
     * be 0. Callers may mutate the ByteBuffer (eg. through relative-read operations), so
     * implementations must return a new ByteBuffer or slice for each call.
     */
    @CalledByNative("I420Buffer") ByteBuffer getDataY();
    /**
     * Returns a direct ByteBuffer containing U-plane data. The buffer capacity is at least
     * getStrideU() * ((getHeight() + 1) / 2) bytes. The position of the returned buffer is ignored
     * and must be 0. Callers may mutate the ByteBuffer (eg. through relative-read operations), so
     * implementations must return a new ByteBuffer or slice for each call.
     */
    @CalledByNative("I420Buffer") ByteBuffer getDataU();
    /**
     * Returns a direct ByteBuffer containing V-plane data. The buffer capacity is at least
     * getStrideV() * ((getHeight() + 1) / 2) bytes. The position of the returned buffer is ignored
     * and must be 0. Callers may mutate the ByteBuffer (eg. through relative-read operations), so
     * implementations must return a new ByteBuffer or slice for each call.
     */
    @CalledByNative("I420Buffer") ByteBuffer getDataV();

    @CalledByNative("I420Buffer") int getStrideY();
    @CalledByNative("I420Buffer") int getStrideU();
    @CalledByNative("I420Buffer") int getStrideV();
  }

  /**
   * Interface for buffers that are stored as a single texture, either in OES or RGB format.
   */
  public interface TextureBuffer extends Buffer {
    enum Type {
      OES(GLES11Ext.GL_TEXTURE_EXTERNAL_OES),
      RGB(GLES20.GL_TEXTURE_2D);

      private final int glTarget;

      private Type(final int glTarget) {
        this.glTarget = glTarget;
      }

      public int getGlTarget() {
        return glTarget;
      }
    }

    Type getType();
    int getTextureId();

    /**
     * Retrieve the transform matrix associated with the frame. This transform matrix maps 2D
     * homogeneous coordinates of the form (s, t, 1) with s and t in the inclusive range [0, 1] to
     * the coordinate that should be used to sample that location from the buffer.
     */
    Matrix getTransformMatrix();
  }

  private final Buffer buffer;
  private final int rotation;
  private final long timestampNs;

  /**
   * Constructs a new VideoFrame backed by the given {@code buffer}.
   *
   * @note Ownership of the buffer object is tranferred to the new VideoFrame.
   */
  @CalledByNative
  public VideoFrame(Buffer buffer, int rotation, long timestampNs) {
    if (buffer == null) {
      throw new IllegalArgumentException("buffer not allowed to be null");
    }
    if (rotation % 90 != 0) {
      throw new IllegalArgumentException("rotation must be a multiple of 90");
    }
    this.buffer = buffer;
    this.rotation = rotation;
    this.timestampNs = timestampNs;
  }

  @CalledByNative
  public Buffer getBuffer() {
    return buffer;
  }

  /**
   * Rotation of the frame in degrees.
   */
  @CalledByNative
  public int getRotation() {
    return rotation;
  }

  /**
   * Timestamp of the frame in nano seconds.
   */
  @CalledByNative
  public long getTimestampNs() {
    return timestampNs;
  }

  public int getRotatedWidth() {
    if (rotation % 180 == 0) {
      return buffer.getWidth();
    }
    return buffer.getHeight();
  }

  public int getRotatedHeight() {
    if (rotation % 180 == 0) {
      return buffer.getHeight();
    }
    return buffer.getWidth();
  }

  @Override
  public void retain() {
    buffer.retain();
  }

  @Override
  @CalledByNative
  public void release() {
    buffer.release();
  }
}