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* Copyright (c) 2015 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.
#include <vector>
#include "api/scoped_refptr.h"
#include "rtc_base/buffer.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/ref_count.h"
struct vpx_codec_ctx;
struct vpx_codec_frame_buffer;
namespace webrtc {
// This memory pool is used to serve buffers to libvpx for decoding purposes in
// VP9, which is set up in InitializeVPXUsePool. After the initialization any
// time libvpx wants to decode a frame it will use buffers provided and released
// through VpxGetFrameBuffer and VpxReleaseFrameBuffer.
// The benefit of owning the pool that libvpx relies on for decoding is that the
// decoded frames returned by libvpx (from vpx_codec_get_frame) use parts of our
// buffers for the decoded image data. By retaining ownership of this buffer
// using scoped_refptr, the image buffer can be reused by VideoFrames and no
// frame copy has to occur during decoding and frame delivery.
// Pseudo example usage case:
// Vp9FrameBufferPool pool;
// pool.InitializeVpxUsePool(decoder_ctx);
// ...
// // During decoding, libvpx will get and release buffers from the pool.
// vpx_codec_decode(decoder_ctx, ...);
// vpx_image_t* img = vpx_codec_get_frame(decoder_ctx, &iter);
// // Important to use scoped_refptr to protect it against being recycled by
// // the pool.
// scoped_refptr<Vp9FrameBuffer> img_buffer = (Vp9FrameBuffer*)img->fb_priv;
// ...
// // Destroying the codec will make libvpx release any buffers it was using.
// vpx_codec_destroy(decoder_ctx);
class Vp9FrameBufferPool {
class Vp9FrameBuffer : public rtc::RefCountInterface {
uint8_t* GetData();
size_t GetDataSize() const;
void SetSize(size_t size);
virtual bool HasOneRef() const = 0;
// Data as an easily resizable buffer.
rtc::Buffer data_;
// Configures libvpx to, in the specified context, use this memory pool for
// buffers used to decompress frames. This is only supported for VP9.
bool InitializeVpxUsePool(vpx_codec_ctx* vpx_codec_context);
// Gets a frame buffer of at least |min_size|, recycling an available one or
// creating a new one. When no longer referenced from the outside the buffer
// becomes recyclable.
rtc::scoped_refptr<Vp9FrameBuffer> GetFrameBuffer(size_t min_size);
// Gets the number of buffers currently in use (not ready to be recycled).
int GetNumBuffersInUse() const;
// Releases allocated buffers, deleting available buffers. Buffers in use are
// not deleted until they are no longer referenced.
void ClearPool();
// InitializeVpxUsePool configures libvpx to call this function when it needs
// a new frame buffer. Parameters:
// |user_priv| Private data passed to libvpx, InitializeVpxUsePool sets it up
// to be a pointer to the pool.
// |min_size| Minimum size needed by libvpx (to decompress a frame).
// |fb| Pointer to the libvpx frame buffer object, this is updated to
// use the pool's buffer.
// Returns 0 on success. Returns < 0 on failure.
static int32_t VpxGetFrameBuffer(void* user_priv,
size_t min_size,
vpx_codec_frame_buffer* fb);
// InitializeVpxUsePool configures libvpx to call this function when it has
// finished using one of the pool's frame buffer. Parameters:
// |user_priv| Private data passed to libvpx, InitializeVpxUsePool sets it up
// to be a pointer to the pool.
// |fb| Pointer to the libvpx frame buffer object, its |priv| will be
// a pointer to one of the pool's Vp9FrameBuffer.
static int32_t VpxReleaseFrameBuffer(void* user_priv,
vpx_codec_frame_buffer* fb);
// Protects |allocated_buffers_|.
rtc::CriticalSection buffers_lock_;
// All buffers, in use or ready to be recycled.
std::vector<rtc::scoped_refptr<Vp9FrameBuffer>> allocated_buffers_
// If more buffers than this are allocated we print warnings and crash if in
// debug mode. VP9 is defined to have 8 reference buffers, of which 3 can be
// referenced by any frame, see
// Assuming VP9 holds on to at most 8 buffers, any more buffers than that
// would have to be by application code. Decoded frames should not be
// referenced for longer than necessary. If we allow ~60 additional buffers
// then the application has ~1 second to e.g. render each frame of a 60 fps
// video.
static const size_t max_num_buffers_ = 68;
} // namespace webrtc
#endif // RTC_ENABLE_VP9