Android - 在使用WebRTC发送到Wowza Streaming Engine之前旋转视频帧

Question

我想使用WebRTC将视频从Android摄像头流式传输到Wowza Streaming Engine（WSE）。当设备处于横向模式时，一切运行良好。然后我尝试通过将设备置于纵向模式来进行流式传输。

我在WSE播放器中注意到的第一件事是视频流已逆时针旋转90度。我发现WebRTC在发送到WSE之前不会旋转从onPreviewFrame API发出的每个视频帧，不幸的是WSE不支持至少到目前为止在他们身边旋转视频帧的任何机制。

所以我检查了WebRTC android原生源代码并修改它以在发送到WSE之前旋转每个视频帧。现在我可以在WSE播放器中以纵向模式看到视频流。

但它有一个问题，有时视频流看起来很奇怪。请参阅以下图片。

A normal image

A weird image

我把相机放到固定位置。 WSE播放器第一次显示第一个，但有时第二个显示。

这里是我改变的WebRTC源代码中的文件。 〜/的WebRTC / src目录/ SDK /安卓/ src目录/ JNI / androidvideotracksource.cc

void AndroidVideoTrackSource::OnByteBufferFrameCaptured(const void* frame_data,
                                                        int length,
                                                        int width,
                                                        int height,
                                                        VideoRotation rotation,
                                                        int64_t timestamp_ns) {
  RTC_DCHECK(camera_thread_checker_.CalledOnValidThread());

  int64_t camera_time_us = timestamp_ns / rtc::kNumNanosecsPerMicrosec;
  int64_t translated_camera_time_us =
      timestamp_aligner_.TranslateTimestamp(camera_time_us, rtc::TimeMicros());

  int adapted_width;
  int adapted_height;
  int crop_width;
  int crop_height;
  int crop_x;
  int crop_y;

  if (!AdaptFrame(width, height, camera_time_us, &adapted_width,
                  &adapted_height, &crop_width, &crop_height, &crop_x,
                  &crop_y)) {
    return;
  }

  const uint8_t* y_plane = static_cast<const uint8_t*>(frame_data);
  const uint8_t* uv_plane = y_plane + width * height;
  const int uv_width = (width + 1) / 2;

  RTC_CHECK_GE(length, width * height + 2 * uv_width * ((height + 1) / 2));

  // Can only crop at even pixels.
  crop_x &= ~1;
  crop_y &= ~1;
  // Crop just by modifying pointers.
  y_plane += width * crop_y + crop_x;
  uv_plane += uv_width * crop_y + crop_x;

  rtc::scoped_refptr<I420Buffer> buffer =
      buffer_pool_.CreateBuffer(adapted_width, adapted_height);

  nv12toi420_scaler_.NV12ToI420Scale(
      y_plane, width, uv_plane, uv_width * 2, crop_width, crop_height,
      buffer->MutableDataY(), buffer->StrideY(),
      // Swap U and V, since we have NV21, not NV12.
      buffer->MutableDataV(), buffer->StrideV(), buffer->MutableDataU(),
      buffer->StrideU(), buffer->width(), buffer->height());

  // TODO: Rotate I420 frame 90 degrees clockwise.
  rtc::scoped_refptr<I420Buffer> rotated_buffer =
      I420Buffer::Rotate(*buffer, kVideoRotation_90);

  OnFrame(VideoFrame(rotated_buffer, rotation, translated_camera_time_us));
}

我添加了这行代码，顺时针旋转I420框架90度。

// TODO: Rotate I420 frame 90 degrees clockwise.
  rtc::scoped_refptr<I420Buffer> rotated_buffer =
      I420Buffer::Rotate(*buffer, kVideoRotation_90);

我将不胜感激任何帮助！

Answer 1

最后，我找到了解决这个问题的解决方案。以下是我的步骤：

第1步：确保将流媒体活动锁定为纵向

第2步：在WebRTC android本机源代码中更改此方法〜/ webrtc / src / sdk / android / src / jni / androidvideotracksource.cc

原始版本：

void AndroidVideoTrackSource::OnByteBufferFrameCaptured(const void* frame_data,
                                                        int length,
                                                        int width,
                                                        int height,
                                                        VideoRotation rotation,
                                                        int64_t timestamp_ns) {
  RTC_DCHECK(camera_thread_checker_.CalledOnValidThread());

  int64_t camera_time_us = timestamp_ns / rtc::kNumNanosecsPerMicrosec;
  int64_t translated_camera_time_us =
      timestamp_aligner_.TranslateTimestamp(camera_time_us, rtc::TimeMicros());

  int adapted_width;
  int adapted_height;
  int crop_width;
  int crop_height;
  int crop_x;
  int crop_y;

  if (!AdaptFrame(width, height, camera_time_us, &adapted_width,
                  &adapted_height, &crop_width, &crop_height, &crop_x,
                  &crop_y)) {
    return;
  }

  const uint8_t* y_plane = static_cast<const uint8_t*>(frame_data);
  const uint8_t* uv_plane = y_plane + width * height;
  const int uv_width = (width + 1) / 2;

  RTC_CHECK_GE(length, width * height + 2 * uv_width * ((height + 1) / 2));

  // Can only crop at even pixels.
  crop_x &= ~1;
  crop_y &= ~1;
  // Crop just by modifying pointers.
  y_plane += width * crop_y + crop_x;
  uv_plane += uv_width * crop_y + crop_x;

  rtc::scoped_refptr<I420Buffer> buffer =
      buffer_pool_.CreateBuffer(adapted_width, adapted_height);

  nv12toi420_scaler_.NV12ToI420Scale(
      y_plane, width, uv_plane, uv_width * 2, crop_width, crop_height,
      buffer->MutableDataY(), buffer->StrideY(),
      // Swap U and V, since we have NV21, not NV12.
      buffer->MutableDataV(), buffer->StrideV(), buffer->MutableDataU(),
      buffer->StrideU(), buffer->width(), buffer->height());

  OnFrame(VideoFrame(rotated_buffer, rotation, translated_camera_time_us));
}

修改版本：

void AndroidVideoTrackSource::OnByteBufferFrameCaptured(const void* frame_data,
                                                        int length,
                                                        int width,
                                                        int height,
                                                        VideoRotation rotation,
                                                        int64_t timestamp_ns) {
  RTC_DCHECK(camera_thread_checker_.CalledOnValidThread());

  int64_t camera_time_us = timestamp_ns / rtc::kNumNanosecsPerMicrosec;
  int64_t translated_camera_time_us =
      timestamp_aligner_.TranslateTimestamp(camera_time_us, rtc::TimeMicros());

  int adapted_width;
  int adapted_height;
  int crop_width;
  int crop_height;
  int crop_x;
  int crop_y;

  if (!AdaptFrame(width, height, camera_time_us, &adapted_width,
                  &adapted_height, &crop_width, &crop_height, &crop_x,
                  &crop_y)) {
    return;
  }

  const uint8_t* y_plane = static_cast<const uint8_t*>(frame_data);
  const uint8_t* uv_plane = y_plane + width * height;
  const int uv_width = (width + 1) / 2;

  RTC_CHECK_GE(length, width * height + 2 * uv_width * ((height + 1) / 2));

  // Can only crop at even pixels.
  crop_x &= ~1;
  crop_y &= ~1;
  // Crop just by modifying pointers.
  y_plane += width * crop_y + crop_x;
  uv_plane += uv_width * crop_y + crop_x;

  rtc::scoped_refptr<I420Buffer> buffer =
      buffer_pool_.CreateBuffer(adapted_width, adapted_height);

  nv12toi420_scaler_.NV12ToI420Scale(
      y_plane, width, uv_plane, uv_width * 2, crop_width, crop_height,
      buffer->MutableDataY(), buffer->StrideY(),
      // Swap U and V, since we have NV21, not NV12.
      buffer->MutableDataV(), buffer->StrideV(), buffer->MutableDataU(),
      buffer->StrideU(), buffer->width(), buffer->height());

  // TODO: Comment out this line of code to apply custom code.
  // OnFrame(VideoFrame(buffer, rotation, translated_camera_time_us));

  // TODO: The custom code to rotate video frame before passing
  // to next layers of WebRTC.

  // Rotate I420 frame rotation degrees.
  // Value of the rotation is 90 or 270 based on camera orientation.
  rtc::scoped_refptr<I420Buffer> rotated_buffer =
      I420Buffer::Rotate(*buffer, rotation);

  // Make sure the I420 frame has valid side in portrait mode.
  rtc::scoped_refptr<I420Buffer> final_buffer =
      buffer_pool_.CreateBuffer(height, width);
  final_buffer->ScaleFrom(*rotated_buffer);

  // After rotating the I420 frame, set value of the rotation to 0.
  // This mean we do not want to rotate the frame in next layers anymore.
  rotation = kVideoRotation_0;

  // Pass processed frame to the next layers.
  OnFrame(VideoFrame(final_buffer, rotation, translated_camera_time_us));
}

现在我的流在Streaming Wowza Engine Player上完美显示。