Load CMA backend from shared library

chromecast/media/cma/base/decoder_buffer_adapter.h

 // Copyright 2014 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.
 
 #ifndef CHROMECAST_MEDIA_CMA_BASE_DECODER_BUFFER_ADAPTER_H_
 #define CHROMECAST_MEDIA_CMA_BASE_DECODER_BUFFER_ADAPTER_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "chromecast/media/cma/base/decoder_buffer_base.h"
 
 namespace media {
 class DecoderBuffer;
 }
 
 namespace chromecast {
 namespace media {
 
 // DecoderBufferAdapter wraps a ::media::DecoderBuffer
 // into a DecoderBufferBase.
 class DecoderBufferAdapter : public DecoderBufferBase {

[alokp, 2015/08/10 22:06:56]

Would it be better to derive DecoderBufferAdapter from CastDecoderBuffer?

With this API I have to allocate too many tiny objects when I need to pass a
media::DecoderBuffer.

media::DecoderBuffer -> DecoderBufferAdapter -> CastDecoderBufferImpl

If DecoderBufferAdapter derived from CastDecoderBuffer directly, we would save
one allocation, which may be significant since it is being done for each media
frame. We still hold a scoped_refptr to ::media::DecoderBuffer, so there is no
change to memory management.

[halliwell, 2015/08/10 22:28:04]

Not possible right now: this would in fact be a change in memory management.  We
still rely on passing a refcounted DecoderBufferBase around.

Of course, it's not an ideal design, and is something we could look at fixing in
the future.

  public:
   // Using explicit constructor without providing stream Id will set it to
   // kPrimary by default.
   explicit DecoderBufferAdapter(
       const scoped_refptr<::media::DecoderBuffer>& buffer);
   DecoderBufferAdapter(
       StreamId stream_id, const scoped_refptr<::media::DecoderBuffer>& buffer);
 
   // DecoderBufferBase implementation.
   StreamId stream_id() const override;
   base::TimeDelta timestamp() const override;
-  void set_timestamp(const base::TimeDelta& timestamp) override;
+  void set_timestamp(base::TimeDelta timestamp) override;
   const uint8* data() const override;
   uint8* writable_data() const override;
   size_t data_size() const override;
-  const ::media::DecryptConfig* decrypt_config() const override;
+  const CastDecryptConfig* decrypt_config() const override;
   bool end_of_stream() const override;
 
  private:
   ~DecoderBufferAdapter() override;
 
   StreamId stream_id_;
   scoped_refptr<::media::DecoderBuffer> const buffer_;
+  mutable scoped_ptr<CastDecryptConfig> decrypt_config_;
 
   DISALLOW_COPY_AND_ASSIGN(DecoderBufferAdapter);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BASE_DECODER_BUFFER_ADAPTER_H_