Added EncodedImage::GetBufferPaddingBytes.

The FFmpeg video decoder requires up to 8 additional bytes to be allocated for its encoded image buffer input, due to optimized byte readers over-reading on some platforms.
We plan to use FFmpeg for a soon-to-land H.264 enc/dec.

This CL adds support for padding encoded image buffers based on codec type, and makes sure calls to VCMEncodedFrame::VerifyAndAllocate use the padding.

All padding constants are 0 but making H.264 pad with 8 bytes will be a one-line change.

Also, added -framework CoreFoundation to webrtc_h264_video_toolbox which was missing.

BUG=chromium:468365
BUG=https://bugs.chromium.org/p/webrtc/issues/detail?id=5424
NOTRY=True

Review URL: https://codereview.webrtc.org/1602523004

Cr-Commit-Position: refs/heads/master@{#11337}

webrtc/common_video/video_frame.cc

@@ -19,6 +19,10 @@
 
 namespace webrtc {
 
+// TODO(hbos): The FFmpeg video decoder will require up to 8 bytes, update this
+// when the FFmpeg decoder is added.
+const size_t EncodedImage::kBufferPaddingBytesH264 = 0;
+
 bool EqualPlane(const uint8_t* data1,
                 const uint8_t* data2,
                 int stride,
@@ -242,4 +246,22 @@ bool VideoFrame::EqualsFrame(const VideoFrame& frame) const {
                     stride(kVPlane), half_width, half_height);
 }
 
+size_t EncodedImage::GetBufferPaddingBytes(VideoCodecType codec_type) {
+  switch (codec_type) {
+    case kVideoCodecVP8:
+    case kVideoCodecVP9:
+      return 0;
+    case kVideoCodecH264:
+      return kBufferPaddingBytesH264;
+    case kVideoCodecI420:
+    case kVideoCodecRED:
+    case kVideoCodecULPFEC:
+    case kVideoCodecGeneric:
+    case kVideoCodecUnknown:
+      return 0;
+  }
+  RTC_NOTREACHED();
+  return 0;
+}
+
 }  // namespace webrtc

webrtc/modules/video_coding/codecs/h264/h264.gypi

@@ -50,6 +50,7 @@
           'link_settings': {
             'xcode_settings': {
               'OTHER_LDFLAGS': [
+                '-framework CoreFoundation',
                 '-framework CoreMedia',
                 '-framework CoreVideo',
                 '-framework VideoToolbox',

webrtc/modules/video_coding/encoded_frame.cc

@@ -41,7 +41,8 @@ VCMEncodedFrame::VCMEncodedFrame(const webrtc::EncodedImage& rhs)
   _size = 0;
   _length = 0;
   if (rhs._buffer != NULL) {
-    VerifyAndAllocate(rhs._length);
+    VerifyAndAllocate(rhs._length +
+                      EncodedImage::GetBufferPaddingBytes(_codec));
     memcpy(_buffer, rhs._buffer, rhs._length);
   }
 }
@@ -60,7 +61,8 @@ VCMEncodedFrame::VCMEncodedFrame(const VCMEncodedFrame& rhs)
   _size = 0;
   _length = 0;
   if (rhs._buffer != NULL) {
-    VerifyAndAllocate(rhs._length);
+    VerifyAndAllocate(rhs._length +
+                      EncodedImage::GetBufferPaddingBytes(_codec));
     memcpy(_buffer, rhs._buffer, rhs._length);
     _length = rhs._length;
   }

webrtc/modules/video_coding/frame_buffer.cc

@@ -105,7 +105,8 @@ VCMFrameBufferEnum VCMFrameBuffer::InsertPacket(
 
   uint32_t requiredSizeBytes =
       Length() + packet.sizeBytes +
-      (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
+      (packet.insertStartCode ? kH264StartCodeLengthBytes : 0) +
+      EncodedImage::GetBufferPaddingBytes(packet.codec);
   if (requiredSizeBytes >= _size) {
     const uint8_t* prevBuffer = _buffer;
     const uint32_t increments =

webrtc/video_frame.h

@@ -173,6 +173,12 @@ class VideoFrame {
 // TODO(pbos): Rename EncodedFrame and reformat this class' members.
 class EncodedImage {
  public:
+  static const size_t kBufferPaddingBytesH264;
+
+  // Some decoders require encoded image buffers to be padded with a small
+  // number of additional bytes (due to over-reading byte readers).
+  static size_t GetBufferPaddingBytes(VideoCodecType codec_type);
+
   EncodedImage() : EncodedImage(nullptr, 0, 0) {}
   EncodedImage(uint8_t* buffer, size_t length, size_t size)
       : _buffer(buffer), _length(length), _size(size) {}