// 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/filters/vpx_video_decoder.h"

#include <algorithm>
#include <string>
#include <vector>

#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/stl_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/sys_byteorder.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/decoder_buffer.h"
#include "media/base/demuxer_stream.h"
#include "media/base/limits.h"
#include "media/base/media_switches.h"
#include "media/base/pipeline.h"
#include "media/base/video_decoder_config.h"
#include "media/base/video_frame.h"
#include "media/base/video_util.h"

// Include libvpx header files.
// VPX_CODEC_DISABLE_COMPAT excludes parts of the libvpx API that provide
// backwards compatibility for legacy applications using the library.
#define VPX_CODEC_DISABLE_COMPAT 1
extern "C" {
#include "third_party/libvpx/source/libvpx/vpx/vpx_decoder.h"
#include "third_party/libvpx/source/libvpx/vpx/vpx_frame_buffer.h"
#include "third_party/libvpx/source/libvpx/vpx/vp8dx.h"
}

namespace media {

// Always try to use three threads for video decoding.  There is little reason
// not to since current day CPUs tend to be multi-core and we measured
// performance benefits on older machines such as P4s with hyperthreading.
static const int kDecodeThreads = 2;
static const int kMaxDecodeThreads = 16;

// Returns the number of threads.
static int GetThreadCount(const VideoDecoderConfig& config) {
  // Refer to http://crbug.com/93932 for tsan suppressions on decoding.
  int decode_threads = kDecodeThreads;

  const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
  std::string threads(cmd_line->GetSwitchValueASCII(switches::kVideoThreads));
  if (threads.empty() || !base::StringToInt(threads, &decode_threads)) {
    if (config.codec() == kCodecVP9) {
      // For VP9 decode when using the default thread count, increase the number
      // of decode threads to equal the maximum number of tiles possible for
      // higher resolution streams.
      if (config.coded_size().width() >= 2048)
        decode_threads = 8;
      else if (config.coded_size().width() >= 1024)
        decode_threads = 4;
    }

    return decode_threads;
  }

  decode_threads = std::max(decode_threads, 0);
  decode_threads = std::min(decode_threads, kMaxDecodeThreads);
  return decode_threads;
}

// Maximum number of frame buffers that can be used (by both chromium and libvpx
// combined) for VP9 Decoding.
// TODO(vigneshv): Investigate if this can be relaxed to a higher number.
static const uint32 kVP9MaxFrameBuffers = VP9_MAXIMUM_REF_BUFFERS +
                                          VPX_MAXIMUM_WORK_BUFFERS +
                                          limits::kMaxVideoFrames;

class VpxVideoDecoder::MemoryPool
    : public base::RefCountedThreadSafe<VpxVideoDecoder::MemoryPool> {
 public:
  MemoryPool();

  // Callback that will be called by libvpx when it needs a frame buffer.
  // Parameters:
  // |user_priv|  Private data passed to libvpx (pointer to memory pool).
  // |min_size|   Minimum size needed by libvpx to decompress the next frame.
  // |fb|         Pointer to the frame buffer to update.
  // Returns 0 on success. Returns < 0 on failure.
  static int32 GetVP9FrameBuffer(void* user_priv, size_t min_size,
                                 vpx_codec_frame_buffer* fb);

  // Callback that will be called by libvpx when the frame buffer is no longer
  // being used by libvpx. Parameters:
  // |user_priv|  Private data passed to libvpx (pointer to memory pool).
  // |fb|         Pointer to the frame buffer that's being released.
  static int32 ReleaseVP9FrameBuffer(void *user_priv,
                                     vpx_codec_frame_buffer *fb);

  // Generates a "no_longer_needed" closure that holds a reference
  // to this pool.
  base::Closure CreateFrameCallback(void* fb_priv_data);

 private:
  friend class base::RefCountedThreadSafe<VpxVideoDecoder::MemoryPool>;
  ~MemoryPool();

  // Reference counted frame buffers used for VP9 decoding. Reference counting
  // is done manually because both chromium and libvpx has to release this
  // before a buffer can be re-used.
  struct VP9FrameBuffer {
    VP9FrameBuffer() : ref_cnt(0) {}
    std::vector<uint8> data;
    uint32 ref_cnt;
  };

  // Gets the next available frame buffer for use by libvpx.
  VP9FrameBuffer* GetFreeFrameBuffer(size_t min_size);

  // Method that gets called when a VideoFrame that references this pool gets
  // destroyed.
  void OnVideoFrameDestroyed(VP9FrameBuffer* frame_buffer);

  // Frame buffers to be used by libvpx for VP9 Decoding.
  std::vector<VP9FrameBuffer*> frame_buffers_;

  DISALLOW_COPY_AND_ASSIGN(MemoryPool);
};

VpxVideoDecoder::MemoryPool::MemoryPool() {}

VpxVideoDecoder::MemoryPool::~MemoryPool() {
  STLDeleteElements(&frame_buffers_);
}

VpxVideoDecoder::MemoryPool::VP9FrameBuffer*
    VpxVideoDecoder::MemoryPool::GetFreeFrameBuffer(size_t min_size) {
  // Check if a free frame buffer exists.
  size_t i = 0;
  for (; i < frame_buffers_.size(); ++i) {
    if (frame_buffers_[i]->ref_cnt == 0)
      break;
  }

  if (i == frame_buffers_.size()) {
    // Maximum number of frame buffers reached.
    if (i == kVP9MaxFrameBuffers)
      return NULL;

    // Create a new frame buffer.
    frame_buffers_.push_back(new VP9FrameBuffer());
  }

  // Resize the frame buffer if necessary.
  if (frame_buffers_[i]->data.size() < min_size)
    frame_buffers_[i]->data.resize(min_size);
  return frame_buffers_[i];
}

int32 VpxVideoDecoder::MemoryPool::GetVP9FrameBuffer(
    void* user_priv, size_t min_size, vpx_codec_frame_buffer* fb) {
  DCHECK(user_priv);
  DCHECK(fb);

  VpxVideoDecoder::MemoryPool* memory_pool =
      static_cast<VpxVideoDecoder::MemoryPool*>(user_priv);

  VP9FrameBuffer* fb_to_use = memory_pool->GetFreeFrameBuffer(min_size);
  if (fb_to_use == NULL)
    return -1;

  fb->data = &fb_to_use->data[0];
  fb->size = fb_to_use->data.size();
  ++fb_to_use->ref_cnt;

  // Set the frame buffer's private data to point at the external frame buffer.
  fb->priv = static_cast<void*>(fb_to_use);
  return 0;
}

int32 VpxVideoDecoder::MemoryPool::ReleaseVP9FrameBuffer(
    void *user_priv, vpx_codec_frame_buffer *fb) {
  VP9FrameBuffer* frame_buffer = static_cast<VP9FrameBuffer*>(fb->priv);
  --frame_buffer->ref_cnt;
  return 0;
}

base::Closure VpxVideoDecoder::MemoryPool::CreateFrameCallback(
    void* fb_priv_data) {
  VP9FrameBuffer* frame_buffer = static_cast<VP9FrameBuffer*>(fb_priv_data);
  ++frame_buffer->ref_cnt;
  return BindToCurrentLoop(
             base::Bind(&MemoryPool::OnVideoFrameDestroyed, this,
                        frame_buffer));
}

void VpxVideoDecoder::MemoryPool::OnVideoFrameDestroyed(
    VP9FrameBuffer* frame_buffer) {
  --frame_buffer->ref_cnt;
}

VpxVideoDecoder::VpxVideoDecoder(
    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
    : task_runner_(task_runner),
      state_(kUninitialized),
      vpx_codec_(NULL),
      vpx_codec_alpha_(NULL) {}

VpxVideoDecoder::~VpxVideoDecoder() {
  DCHECK_EQ(kUninitialized, state_);
  CloseDecoder();
}

void VpxVideoDecoder::Initialize(const VideoDecoderConfig& config,
                                 bool low_delay,
                                 const PipelineStatusCB& status_cb,
                                 const OutputCB& output_cb) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(config.IsValidConfig());
  DCHECK(!config.is_encrypted());
  DCHECK(decode_cb_.is_null());

  if (!ConfigureDecoder(config)) {
    status_cb.Run(DECODER_ERROR_NOT_SUPPORTED);
    return;
  }

  // Success!
  config_ = config;
  state_ = kNormal;
  output_cb_ = BindToCurrentLoop(output_cb);
  status_cb.Run(PIPELINE_OK);
}

static vpx_codec_ctx* InitializeVpxContext(vpx_codec_ctx* context,
                                           const VideoDecoderConfig& config) {
  context = new vpx_codec_ctx();
  vpx_codec_dec_cfg_t vpx_config = {0};
  vpx_config.w = config.coded_size().width();
  vpx_config.h = config.coded_size().height();
  vpx_config.threads = GetThreadCount(config);

  vpx_codec_err_t status = vpx_codec_dec_init(context,
                                              config.codec() == kCodecVP9 ?
                                                  vpx_codec_vp9_dx() :
                                                  vpx_codec_vp8_dx(),
                                              &vpx_config,
                                              0);
  if (status != VPX_CODEC_OK) {
    LOG(ERROR) << "vpx_codec_dec_init failed, status=" << status;
    delete context;
    return NULL;
  }
  return context;
}

bool VpxVideoDecoder::ConfigureDecoder(const VideoDecoderConfig& config) {
  if (config.codec() != kCodecVP8 && config.codec() != kCodecVP9)
    return false;

  // In VP8 videos, only those with alpha are handled by VpxVideoDecoder. All
  // other VP8 videos go to FFmpegVideoDecoder.
  if (config.codec() == kCodecVP8 && config.format() != VideoFrame::YV12A)
    return false;

  CloseDecoder();

  vpx_codec_ = InitializeVpxContext(vpx_codec_, config);
  if (!vpx_codec_)
    return false;

  // We use our own buffers for VP9 so that there is no need to copy data after
  // decoding.
  if (config.codec() == kCodecVP9) {
    memory_pool_ = new MemoryPool();
    if (vpx_codec_set_frame_buffer_functions(vpx_codec_,
                                             &MemoryPool::GetVP9FrameBuffer,
                                             &MemoryPool::ReleaseVP9FrameBuffer,
                                             memory_pool_)) {
      LOG(ERROR) << "Failed to configure external buffers.";
      return false;
    }
  }

  if (config.format() == VideoFrame::YV12A) {
    vpx_codec_alpha_ = InitializeVpxContext(vpx_codec_alpha_, config);
    if (!vpx_codec_alpha_)
      return false;
  }

  return true;
}

void VpxVideoDecoder::CloseDecoder() {
  if (vpx_codec_) {
    vpx_codec_destroy(vpx_codec_);
    delete vpx_codec_;
    vpx_codec_ = NULL;
    memory_pool_ = NULL;
  }
  if (vpx_codec_alpha_) {
    vpx_codec_destroy(vpx_codec_alpha_);
    delete vpx_codec_alpha_;
    vpx_codec_alpha_ = NULL;
  }
}

void VpxVideoDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
                             const DecodeCB& decode_cb) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(!decode_cb.is_null());
  CHECK_NE(state_, kUninitialized);
  CHECK(decode_cb_.is_null()) << "Overlapping decodes are not supported.";

  decode_cb_ = BindToCurrentLoop(decode_cb);

  if (state_ == kError) {
    base::ResetAndReturn(&decode_cb_).Run(kDecodeError);
    return;
  }

  // Return empty frames if decoding has finished.
  if (state_ == kDecodeFinished) {
    base::ResetAndReturn(&decode_cb_).Run(kOk);
    return;
  }

  DecodeBuffer(buffer);
}

void VpxVideoDecoder::Reset(const base::Closure& closure) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(decode_cb_.is_null());

  state_ = kNormal;
  task_runner_->PostTask(FROM_HERE, closure);
}

void VpxVideoDecoder::Stop() {
  DCHECK(task_runner_->BelongsToCurrentThread());

  state_ = kUninitialized;
}

void VpxVideoDecoder::DecodeBuffer(const scoped_refptr<DecoderBuffer>& buffer) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_NE(state_, kUninitialized);
  DCHECK_NE(state_, kDecodeFinished);
  DCHECK_NE(state_, kError);
  DCHECK(!decode_cb_.is_null());
  DCHECK(buffer);

  // Transition to kDecodeFinished on the first end of stream buffer.
  if (state_ == kNormal && buffer->end_of_stream()) {
    state_ = kDecodeFinished;
    base::ResetAndReturn(&decode_cb_).Run(kOk);
    return;
  }

  scoped_refptr<VideoFrame> video_frame;
  if (!VpxDecode(buffer, &video_frame)) {
    state_ = kError;
    base::ResetAndReturn(&decode_cb_).Run(kDecodeError);
    return;
  }

  base::ResetAndReturn(&decode_cb_).Run(kOk);

  if (video_frame)
    output_cb_.Run(video_frame);
}

bool VpxVideoDecoder::VpxDecode(const scoped_refptr<DecoderBuffer>& buffer,
                                scoped_refptr<VideoFrame>* video_frame) {
  DCHECK(video_frame);
  DCHECK(!buffer->end_of_stream());

  // Pass |buffer| to libvpx.
  int64 timestamp = buffer->timestamp().InMicroseconds();
  void* user_priv = reinterpret_cast<void*>(&timestamp);
  vpx_codec_err_t status = vpx_codec_decode(vpx_codec_,
                                            buffer->data(),
                                            buffer->data_size(),
                                            user_priv,
                                            0);
  if (status != VPX_CODEC_OK) {
    LOG(ERROR) << "vpx_codec_decode() failed, status=" << status;
    return false;
  }

  // Gets pointer to decoded data.
  vpx_codec_iter_t iter = NULL;
  const vpx_image_t* vpx_image = vpx_codec_get_frame(vpx_codec_, &iter);
  if (!vpx_image) {
    *video_frame = NULL;
    return true;
  }

  if (vpx_image->user_priv != reinterpret_cast<void*>(&timestamp)) {
    LOG(ERROR) << "Invalid output timestamp.";
    return false;
  }

  const vpx_image_t* vpx_image_alpha = NULL;
  if (vpx_codec_alpha_ && buffer->side_data_size() >= 8) {
    // Pass alpha data to libvpx.
    int64 timestamp_alpha = buffer->timestamp().InMicroseconds();
    void* user_priv_alpha = reinterpret_cast<void*>(&timestamp_alpha);

    // First 8 bytes of side data is side_data_id in big endian.
    const uint64 side_data_id = base::NetToHost64(
        *(reinterpret_cast<const uint64*>(buffer->side_data())));
    if (side_data_id == 1) {
      status = vpx_codec_decode(vpx_codec_alpha_,
                                buffer->side_data() + 8,
                                buffer->side_data_size() - 8,
                                user_priv_alpha,
                                0);

      if (status != VPX_CODEC_OK) {
        LOG(ERROR) << "vpx_codec_decode() failed on alpha, status=" << status;
        return false;
      }

      // Gets pointer to decoded data.
      vpx_codec_iter_t iter_alpha = NULL;
      vpx_image_alpha = vpx_codec_get_frame(vpx_codec_alpha_, &iter_alpha);
      if (!vpx_image_alpha) {
        *video_frame = NULL;
        return true;
      }

      if (vpx_image_alpha->user_priv !=
          reinterpret_cast<void*>(&timestamp_alpha)) {
        LOG(ERROR) << "Invalid output timestamp on alpha.";
        return false;
      }
    }
  }

  CopyVpxImageTo(vpx_image, vpx_image_alpha, video_frame);
  (*video_frame)->set_timestamp(base::TimeDelta::FromMicroseconds(timestamp));
  return true;
}

void VpxVideoDecoder::CopyVpxImageTo(const vpx_image* vpx_image,
                                     const struct vpx_image* vpx_image_alpha,
                                     scoped_refptr<VideoFrame>* video_frame) {
  CHECK(vpx_image);
  CHECK(vpx_image->fmt == VPX_IMG_FMT_I420 ||
        vpx_image->fmt == VPX_IMG_FMT_YV12 ||
        vpx_image->fmt == VPX_IMG_FMT_I444);

  VideoFrame::Format codec_format = VideoFrame::YV12;
  int uv_rows = (vpx_image->d_h + 1) / 2;

  if (vpx_image->fmt == VPX_IMG_FMT_I444) {
    CHECK(!vpx_codec_alpha_);
    codec_format = VideoFrame::YV24;
    uv_rows = vpx_image->d_h;
  } else if (vpx_codec_alpha_) {
    codec_format = VideoFrame::YV12A;
  }

  gfx::Size size(vpx_image->d_w, vpx_image->d_h);

  if (!vpx_codec_alpha_ && memory_pool_) {
    *video_frame = VideoFrame::WrapExternalYuvData(
        codec_format,
        size, gfx::Rect(size), config_.natural_size(),
        vpx_image->stride[VPX_PLANE_Y],
        vpx_image->stride[VPX_PLANE_U],
        vpx_image->stride[VPX_PLANE_V],
        vpx_image->planes[VPX_PLANE_Y],
        vpx_image->planes[VPX_PLANE_U],
        vpx_image->planes[VPX_PLANE_V],
        kNoTimestamp(),
        memory_pool_->CreateFrameCallback(vpx_image->fb_priv));
    return;
  }

  *video_frame = frame_pool_.CreateFrame(
      codec_format,
      size,
      gfx::Rect(size),
      config_.natural_size(),
      kNoTimestamp());

  CopyYPlane(vpx_image->planes[VPX_PLANE_Y],
             vpx_image->stride[VPX_PLANE_Y],
             vpx_image->d_h,
             video_frame->get());
  CopyUPlane(vpx_image->planes[VPX_PLANE_U],
             vpx_image->stride[VPX_PLANE_U],
             uv_rows,
             video_frame->get());
  CopyVPlane(vpx_image->planes[VPX_PLANE_V],
             vpx_image->stride[VPX_PLANE_V],
             uv_rows,
             video_frame->get());
  if (!vpx_codec_alpha_)
    return;
  if (!vpx_image_alpha) {
    MakeOpaqueAPlane(
        vpx_image->stride[VPX_PLANE_Y], vpx_image->d_h, video_frame->get());
    return;
  }
  CopyAPlane(vpx_image_alpha->planes[VPX_PLANE_Y],
             vpx_image->stride[VPX_PLANE_Y],
             vpx_image->d_h,
             video_frame->get());
}

}  // namespace media