Adding VP8 Alpha support in Media Source

media/base/decoder_buffer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/decoder_buffer.h"
 
 #include "base/logging.h"
 #include "media/base/decrypt_config.h"
 
 namespace media {
@@ skipping 15 matching lines @@
   Initialize();
   memcpy(data_.get(), data, size_);
 }
 
 DecoderBuffer::DecoderBuffer(const uint8* data, int size,
                              const uint8* side_data, int side_data_size)
     : size_(size),
       side_data_size_(side_data_size) {
   if (!data) {
     CHECK_EQ(size_, 0);
     return;

[acolwell GONE FROM CHROMIUM, 2013/05/21 17:14:11]

Should there be a CHECK(!side_data) here? I'm assuming side_data only buffers
are not allowed.

[vignesh, 2013/05/21 18:57:56]

Done.

   }
 
   Initialize();
   memcpy(data_.get(), data, size_);
-  memcpy(side_data_.get(), side_data, side_data_size_);
+  if (side_data_size > 0)

[fgalligan1, 2013/05/21 00:02:43]

nit: Check side_data_size_

[vignesh, 2013/05/21 18:57:56]

Done.

+    memcpy(side_data_.get(), side_data, side_data_size_);

[acolwell GONE FROM CHROMIUM, 2013/05/21 17:14:11]

Why is this change needed? Are you seeing negative values passed in? If you are
worried about this, just put DCHECK_GE(side_data_size, 0); at the top of the
method.

[vignesh, 2013/05/21 18:57:56]

I made this change because i replaced the private constructor in
StreamParserBuffer to take side_data and side_data_size by default (the callers
will pass NULL if there is no side_data). So StreamParserBuffer always calls the
4 arg constructor of DecoderBuffer which gives rise to a possibility of
side_data_size being -1. This possibility didn't exist before. 

In fact, if StreamParserBuffer is the only class that inherits from
DecoderBuffer, we can actually go ahead and remove the 2 arg constructor (the
one without side_data) of DecoderBuffer and make the callers pass NULL if there
is no side_data there as well.

 }
 
 DecoderBuffer::~DecoderBuffer() {}
 
 void DecoderBuffer::Initialize() {
   CHECK_GE(size_, 0);
   data_.reset(reinterpret_cast<uint8*>(
       base::AlignedAlloc(size_ + kPaddingSize, kAlignmentSize)));
   memset(data_.get() + size_, 0, kPaddingSize);
   if (side_data_size_ > 0) {
@@ skipping 95 matching lines @@
   std::ostringstream s;
   s << "timestamp: " << timestamp_.InMicroseconds()
     << " duration: " << duration_.InMicroseconds()
     << " size: " << size_
     << " side_data_size: " << side_data_size_
     << " encrypted: " << (decrypt_config_ != NULL);
   return s.str();
 }
 
 }  // namespace media