Support for video file instead of camera and output video out to file

webrtc/api/android/java/src/org/webrtc/FileVideoCapturer.java

Index: webrtc/api/android/java/src/org/webrtc/FileVideoCapturer.java
diff --git a/webrtc/api/android/java/src/org/webrtc/FileVideoCapturer.java b/webrtc/api/android/java/src/org/webrtc/FileVideoCapturer.java
new file mode 100644
index 0000000000000000000000000000000000000000..9acc31ae7ca361aeecc8a82675e06c04034b195b
--- /dev/null
+++ b/webrtc/api/android/java/src/org/webrtc/FileVideoCapturer.java
@@ -0,0 +1,221 @@
+/*
+ *  Copyright 2016 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.
+ */

[sakal, 2016/09/27 07:54:27]

nit: add empty line

+package org.webrtc;
+
+import android.content.Context;
+import android.os.SystemClock;
+
+import java.util.concurrent.TimeUnit;
+import java.util.Timer;
+import java.util.TimerTask;
+

[sakal, 2016/09/27 07:54:27]

nit: remove empty line

+import java.io.File;
+import java.io.RandomAccessFile;
+import java.io.IOException;
+
+public class FileVideoCapturer implements VideoCapturer {

[sakal, 2016/09/27 07:54:27]

nit: it would be nice to have a simple javadoc about what this class does

+  private interface VideoReader {
+    int getFrameWidth();
+    int getFrameHeight();
+    byte[] getNextFrame();
+    void close();
+  }
+
+  class VideoReaderY4M implements VideoReader {

[magjed_webrtc, 2016/09/26 11:40:01]

Make this class static.

[sakal, 2016/09/27 07:54:27]

And private?

[mandermo, 2016/10/04 14:56:55]

Done.

[mandermo, 2016/10/04 14:56:56]

Made it private static

+    private final static String TAG = "VideoReaderY4M";
+    private int frameWidth;

[magjed_webrtc, 2016/09/26 11:40:02]

make these variables final

[mandermo, 2016/10/04 14:56:55]

Done.

+    private int frameHeight;
+    private int frameSize;
+
+    // First char after header
+    private int videoStart;
+
+    final String Y4M_FRAME_DELIMETER = "FRAME";

[magjed_webrtc, 2016/09/26 11:40:02]

make this private static

[mandermo, 2016/10/04 14:56:56]

Done.

+
+    private RandomAccessFile mediaFileStream;

[sakal, 2016/09/27 07:54:27]

Make this final.

+
+    public int getFrameWidth() {
+      return frameWidth;
+    }
+
+    public int getFrameHeight() {
+      return frameHeight;
+    }
+
+    VideoReaderY4M(String file) throws IOException {

[sakal, 2016/09/27 07:54:27]

public?

[mandermo, 2016/10/04 14:56:56]

Done.

+      mediaFileStream = new RandomAccessFile(file, "r");
+      byte[] startData = new byte[1000];

[magjed_webrtc, 2016/09/26 11:40:02]

This is a bit ugly. Is there no elegant way of finding the first occurrence of a
string in a RandomAccessFile?

[mandermo, 2016/10/04 14:56:56]

Done.

[mandermo, 2016/10/04 14:56:56]

Done.

+      mediaFileStream.read(startData);
+
+      String headerAndMore = new String(startData);
+      videoStart = headerAndMore.indexOf(Y4M_FRAME_DELIMETER);
+      if (videoStart == -1) {
+        //throw new RuntimeException("Error reading file");

[magjed_webrtc, 2016/09/26 11:40:01]

You should probably throw here.

[mandermo, 2016/10/04 14:56:55]

Done.

[mandermo, 2016/10/04 14:56:55]

Done.

+        return;
+      }
+      String header = headerAndMore.substring(0, videoStart);
+      mediaFileStream.seek(videoStart);
+      String[] headerTokens = header.split("[\n ]");
+      Logging.d(TAG, "header: " + header + ", headerTokens" + headerTokens);
+      int w = 0;
+      int h = 0;
+      for (String tok : headerTokens) {
+        char c = tok.charAt(0);
+        switch (c) {
+          case 'W':
+            w = Integer.parseInt(tok.substring(1));
+            break;
+          case 'H':
+            h = Integer.parseInt(tok.substring(1));
+            break;
+        }
+      }
+      frameWidth = w;
+      frameHeight = h;
+      frameSize = w * h * 3 / 2;

[magjed_webrtc, 2016/09/26 11:40:01]

have you tried frames with odd width? I think you need to update this code to 'w
* h + 2 * ((w + 1) / 2) * ((h + 1) / 2)'

[sakal, 2016/09/27 07:54:27]

The length of the frame depends on the color space. Maybe we should assert that
the file has the correct color space?

[mandermo, 2016/10/04 14:56:56]

https://wiki.multimedia.cx/index.php?title=YUV4MPEG2 says that you can compute
frame size this way  width * height * 3 / 2 for I420. It does not appear to me
that the container support odd sized frames. Should I do it anyway?

+      Logging.d(TAG, "frame dim: (" + w + ", " + h + ") frameSize: " + frameSize);
+    }
+
+    public byte[] getNextFrame() {
+      byte[] frame = new byte[frameSize];
+      try {
+        if (mediaFileStream.skipBytes(Y4M_FRAME_DELIMETER.length()+1) <

[magjed_webrtc, 2016/09/26 11:40:02]

this doesn't follow the style guide

+            Y4M_FRAME_DELIMETER.length()+1)
+        {
+          // We reach end of file, loop
+          mediaFileStream.seek(videoStart + Y4M_FRAME_DELIMETER.length()+1);
+        }
+        mediaFileStream.readFully(frame);

[sakal, 2016/09/27 07:54:27]

Frames can also have parameters. We should take that into account.

[mandermo, 2016/10/04 14:56:56]

Checks that the frame does not contain any parameters now.

+        byte[] nv12Frame = new byte[frameSize];
+        nativeI420ToNV21(

[sakal, 2016/09/27 07:54:27]

Please add comment why it is called nv12Frame when we use nativeI420ToNV21. I
know in some places we use some trickery to convert between the two. Is it the
case here as well?

[mandermo, 2016/10/04 14:56:56]

Renamed to NV21. Thought they where in NV12 format before.

+            frame, frameWidth, frameHeight, nv12Frame);
+        return nv12Frame;
+      }
+      catch (IOException e) {

[sakal, 2016/09/27 07:54:27]

nit: move to the same line with the closing bracket

+        return null;
+      }
+    }
+
+    public void close() {
+      try {
+        mediaFileStream.close();
+      }
+      catch (IOException e) {
+        Logging.d(TAG, "Problem closing file");

[magjed_webrtc, 2016/09/26 11:40:01]

Log error here instead, i.e. Logging.e.

[mandermo, 2016/10/04 14:56:55]

Done.

[mandermo, 2016/10/04 14:56:55]

Done.

+      }
+    }
+  }
+
+  private final static String TAG = "FileVideoCapturer";
+
+  private VideoReader videoReader;
+
+  private CapturerObserver capturerObserver;
+
+  private Timer timer = new Timer();
+
+  private TimerTask tickTask = new TimerTask() {
+      @Override
+      public void run() {
+        tick(capturerObserver);
+      }
+    };
+
+  private int getFrameWidth() {
+    return videoReader.getFrameWidth();
+  }
+
+  private int getFrameHeight() {
+    return videoReader.getFrameHeight();
+  }
+
+  public FileVideoCapturer(String inputFile) throws IOException {
+    openMediaFile(inputFile);
+  }
+
+  public static FileVideoCapturer create(String inputFile) {
+    try {
+      return new FileVideoCapturer(
+          inputFile);
+    } catch (IOException e) {
+      Logging.e(TAG, "Error opening input file.", e);
+      return null;
+    }
+  }
+
+  private void openMediaFile(String file)
+    throws IOException
+  {
+    try {
+      videoReader = new VideoReaderY4M(file);

[magjed_webrtc, 2016/09/26 11:40:01]

just inline this in the ctor

[mandermo, 2016/10/04 14:56:56]

Done.

+    }
+    catch (IOException e) {
+      Logging.d(TAG, "Could not open video file: " + file);

[magjed_webrtc, 2016/09/26 11:40:02]

We already log in FileVideoCapturer.create so you don't need this one as well.

[mandermo, 2016/10/04 14:56:56]

Done.

+      throw e;
+    }
+  }
+
+  private byte[] getNextFrame() {
+    return videoReader.getNextFrame();
+  }
+
+  public void tick(VideoCapturer.CapturerObserver capturerObserver) {
+    final long captureTimeNs =
+        TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
+
+    byte[] frameData = getNextFrame();
+    capturerObserver.onByteBufferFrameCaptured(
+        frameData,
+        getFrameWidth(),
+        getFrameHeight(),
+        0,
+        captureTimeNs);
+  }
+
+  @Override
+  public void initialize(SurfaceTextureHelper surfaceTextureHelper, Context applicationContext,
+      CapturerObserver capturerObserver) {
+    this.capturerObserver = capturerObserver;
+  }
+
+  @Override
+  public void startCapture(
+      int width, int height, int framerate) {
+    timer.schedule(tickTask, 0, 1000/framerate);
+  }
+
+  @Override
+  public void stopCapture() throws InterruptedException {
+    timer.cancel();
+  }
+
+  @Override
+  public void onOutputFormatRequest(int width, int height, int framerate) {
+    // Empty on purpose
+  }
+
+  @Override
+  public void changeCaptureFormat(int width, int height, int framerate) {
+    // Empty on purpose
+  }
+
+  @Override
+  public void dispose() {
+    videoReader.close();
+  }
+
+  @Override
+  public boolean isScreencast() {
+    return false;
+  }
+
+  public static native void nativeI420ToNV21(byte[] src, int width,
+      int height, byte[] dst);
+}