modules/video_coding refactorings

The main purpose was the interface-> include rename, but other files
were also moved, eliminating the "main" dir.

To avoid breaking downstream, the "interface" directories were copied
into a new "video_coding/include" dir. The old headers got pragma
warnings added about deprecation (a very short deprecation since I plan
to remove them as soon downstream is updated).

Other files also moved:
video_coding/main/source -> video_coding
video_coding/main/test -> video_coding/test

BUG=webrtc:5095
TESTED=Passing compile-trybots with --clobber flag:
git cl try --clobber --bot=win_compile_rel --bot=linux_compile_rel --bot=android_compile_rel --bot=mac_compile_rel --bot=ios_rel --bot=linux_gn_rel --bot=win_x64_gn_rel --bot=mac_x64_gn_rel --bot=android_gn_rel -m tryserver.webrtc

R=stefan@webrtc.org, tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1417283007 .

Cr-Commit-Position: refs/heads/master@{#10694}
diff --git a/webrtc/modules/video_coding/codec_database.cc b/webrtc/modules/video_coding/codec_database.cc
new file mode 100644
index 0000000..d3e2ce4
--- /dev/null
+++ b/webrtc/modules/video_coding/codec_database.cc
@@ -0,0 +1,687 @@
+/*
+ *  Copyright (c) 2012 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 "webrtc/modules/video_coding/codec_database.h"
+
+#include <assert.h>
+
+#include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
+#include "webrtc/engine_configurations.h"
+#ifdef VIDEOCODEC_H264
+#include "webrtc/modules/video_coding/codecs/h264/include/h264.h"
+#endif
+#ifdef VIDEOCODEC_I420
+#include "webrtc/modules/video_coding/codecs/i420/include/i420.h"
+#endif
+#ifdef VIDEOCODEC_VP8
+#include "webrtc/modules/video_coding/codecs/vp8/include/vp8.h"
+#endif
+#ifdef VIDEOCODEC_VP9
+#include "webrtc/modules/video_coding/codecs/vp9/include/vp9.h"
+#endif
+#include "webrtc/modules/video_coding/internal_defines.h"
+
+namespace {
+const size_t kDefaultPayloadSize = 1440;
+const uint8_t kDefaultPayloadType = 100;
+}
+
+namespace webrtc {
+
+VideoCodecVP8 VideoEncoder::GetDefaultVp8Settings() {
+  VideoCodecVP8 vp8_settings;
+  memset(&vp8_settings, 0, sizeof(vp8_settings));
+
+  vp8_settings.resilience = kResilientStream;
+  vp8_settings.numberOfTemporalLayers = 1;
+  vp8_settings.denoisingOn = true;
+  vp8_settings.errorConcealmentOn = false;
+  vp8_settings.automaticResizeOn = false;
+  vp8_settings.frameDroppingOn = true;
+  vp8_settings.keyFrameInterval = 3000;
+
+  return vp8_settings;
+}
+
+VideoCodecVP9 VideoEncoder::GetDefaultVp9Settings() {
+  VideoCodecVP9 vp9_settings;
+  memset(&vp9_settings, 0, sizeof(vp9_settings));
+
+  vp9_settings.resilience = 1;
+  vp9_settings.numberOfTemporalLayers = 1;
+  vp9_settings.denoisingOn = false;
+  vp9_settings.frameDroppingOn = true;
+  vp9_settings.keyFrameInterval = 3000;
+  vp9_settings.adaptiveQpMode = true;
+  vp9_settings.automaticResizeOn = true;
+  vp9_settings.numberOfSpatialLayers = 1;
+  vp9_settings.flexibleMode = false;
+  return vp9_settings;
+}
+
+VideoCodecH264 VideoEncoder::GetDefaultH264Settings() {
+  VideoCodecH264 h264_settings;
+  memset(&h264_settings, 0, sizeof(h264_settings));
+
+  h264_settings.profile = kProfileBase;
+  h264_settings.frameDroppingOn = true;
+  h264_settings.keyFrameInterval = 3000;
+  h264_settings.spsData = NULL;
+  h264_settings.spsLen = 0;
+  h264_settings.ppsData = NULL;
+  h264_settings.ppsLen = 0;
+
+  return h264_settings;
+}
+
+VCMDecoderMapItem::VCMDecoderMapItem(VideoCodec* settings,
+                                     int number_of_cores,
+                                     bool require_key_frame)
+    : settings(settings),
+      number_of_cores(number_of_cores),
+      require_key_frame(require_key_frame) {
+  assert(number_of_cores >= 0);
+}
+
+VCMExtDecoderMapItem::VCMExtDecoderMapItem(
+    VideoDecoder* external_decoder_instance,
+    uint8_t payload_type,
+    bool internal_render_timing)
+    : payload_type(payload_type),
+      external_decoder_instance(external_decoder_instance),
+      internal_render_timing(internal_render_timing) {
+}
+
+VCMCodecDataBase::VCMCodecDataBase(
+    VideoEncoderRateObserver* encoder_rate_observer,
+    VCMEncodedFrameCallback* encoded_frame_callback)
+    : number_of_cores_(0),
+      max_payload_size_(kDefaultPayloadSize),
+      periodic_key_frames_(false),
+      pending_encoder_reset_(true),
+      send_codec_(),
+      receive_codec_(),
+      encoder_payload_type_(0),
+      external_encoder_(NULL),
+      internal_source_(false),
+      encoder_rate_observer_(encoder_rate_observer),
+      encoded_frame_callback_(encoded_frame_callback),
+      ptr_decoder_(NULL),
+      dec_map_(),
+      dec_external_map_() {}
+
+VCMCodecDataBase::~VCMCodecDataBase() {
+  ResetSender();
+  ResetReceiver();
+}
+
+int VCMCodecDataBase::NumberOfCodecs() {
+  return VCM_NUM_VIDEO_CODECS_AVAILABLE;
+}
+
+bool VCMCodecDataBase::Codec(int list_id,
+                             VideoCodec* settings) {
+  if (!settings) {
+    return false;
+  }
+  if (list_id >= VCM_NUM_VIDEO_CODECS_AVAILABLE) {
+    return false;
+  }
+  memset(settings, 0, sizeof(VideoCodec));
+  switch (list_id) {
+#ifdef VIDEOCODEC_VP8
+    case VCM_VP8_IDX: {
+      strncpy(settings->plName, "VP8", 4);
+      settings->codecType = kVideoCodecVP8;
+      // 96 to 127 dynamic payload types for video codecs.
+      settings->plType = kDefaultPayloadType;
+      settings->startBitrate = kDefaultStartBitrateKbps;
+      settings->minBitrate = VCM_MIN_BITRATE;
+      settings->maxBitrate = 0;
+      settings->maxFramerate = VCM_DEFAULT_FRAME_RATE;
+      settings->width = VCM_DEFAULT_CODEC_WIDTH;
+      settings->height = VCM_DEFAULT_CODEC_HEIGHT;
+      settings->numberOfSimulcastStreams = 0;
+      settings->qpMax = 56;
+      settings->codecSpecific.VP8 = VideoEncoder::GetDefaultVp8Settings();
+      return true;
+    }
+#endif
+#ifdef VIDEOCODEC_VP9
+    case VCM_VP9_IDX: {
+      strncpy(settings->plName, "VP9", 4);
+      settings->codecType = kVideoCodecVP9;
+      // 96 to 127 dynamic payload types for video codecs.
+      settings->plType = kDefaultPayloadType;
+      settings->startBitrate = 100;
+      settings->minBitrate = VCM_MIN_BITRATE;
+      settings->maxBitrate = 0;
+      settings->maxFramerate = VCM_DEFAULT_FRAME_RATE;
+      settings->width = VCM_DEFAULT_CODEC_WIDTH;
+      settings->height = VCM_DEFAULT_CODEC_HEIGHT;
+      settings->numberOfSimulcastStreams = 0;
+      settings->qpMax = 56;
+      settings->codecSpecific.VP9 = VideoEncoder::GetDefaultVp9Settings();
+      return true;
+    }
+#endif
+#ifdef VIDEOCODEC_H264
+    case VCM_H264_IDX: {
+      strncpy(settings->plName, "H264", 5);
+      settings->codecType = kVideoCodecH264;
+      // 96 to 127 dynamic payload types for video codecs.
+      settings->plType = kDefaultPayloadType;
+      settings->startBitrate = kDefaultStartBitrateKbps;
+      settings->minBitrate = VCM_MIN_BITRATE;
+      settings->maxBitrate = 0;
+      settings->maxFramerate = VCM_DEFAULT_FRAME_RATE;
+      settings->width = VCM_DEFAULT_CODEC_WIDTH;
+      settings->height = VCM_DEFAULT_CODEC_HEIGHT;
+      settings->numberOfSimulcastStreams = 0;
+      settings->qpMax = 56;
+      settings->codecSpecific.H264 = VideoEncoder::GetDefaultH264Settings();
+      return true;
+    }
+#endif
+#ifdef VIDEOCODEC_I420
+    case VCM_I420_IDX: {
+      strncpy(settings->plName, "I420", 5);
+      settings->codecType = kVideoCodecI420;
+      // 96 to 127 dynamic payload types for video codecs.
+      settings->plType = kDefaultPayloadType;
+      // Bitrate needed for this size and framerate.
+      settings->startBitrate = 3 * VCM_DEFAULT_CODEC_WIDTH *
+                               VCM_DEFAULT_CODEC_HEIGHT * 8 *
+                               VCM_DEFAULT_FRAME_RATE / 1000 / 2;
+      settings->maxBitrate = settings->startBitrate;
+      settings->maxFramerate = VCM_DEFAULT_FRAME_RATE;
+      settings->width = VCM_DEFAULT_CODEC_WIDTH;
+      settings->height = VCM_DEFAULT_CODEC_HEIGHT;
+      settings->minBitrate = VCM_MIN_BITRATE;
+      settings->numberOfSimulcastStreams = 0;
+      return true;
+    }
+#endif
+    default: {
+      return false;
+    }
+  }
+}
+
+bool VCMCodecDataBase::Codec(VideoCodecType codec_type,
+                             VideoCodec* settings) {
+  for (int i = 0; i < VCMCodecDataBase::NumberOfCodecs(); i++) {
+    const bool ret = VCMCodecDataBase::Codec(i, settings);
+    if (!ret) {
+      return false;
+    }
+    if (codec_type == settings->codecType) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void VCMCodecDataBase::ResetSender() {
+  DeleteEncoder();
+  periodic_key_frames_ = false;
+}
+
+// Assuming only one registered encoder - since only one used, no need for more.
+bool VCMCodecDataBase::SetSendCodec(const VideoCodec* send_codec,
+                                    int number_of_cores,
+                                    size_t max_payload_size) {
+  RTC_DCHECK(send_codec);
+  if (max_payload_size == 0) {
+    max_payload_size = kDefaultPayloadSize;
+  }
+  RTC_DCHECK_GE(number_of_cores, 1);
+  RTC_DCHECK_GE(send_codec->plType, 1);
+  // Make sure the start bit rate is sane...
+  RTC_DCHECK_LE(send_codec->startBitrate, 1000000u);
+  RTC_DCHECK(send_codec->codecType != kVideoCodecUnknown);
+  bool reset_required = pending_encoder_reset_;
+  if (number_of_cores_ != number_of_cores) {
+    number_of_cores_ = number_of_cores;
+    reset_required = true;
+  }
+  if (max_payload_size_ != max_payload_size) {
+    max_payload_size_ = max_payload_size;
+    reset_required = true;
+  }
+
+  VideoCodec new_send_codec;
+  memcpy(&new_send_codec, send_codec, sizeof(new_send_codec));
+
+  if (new_send_codec.maxBitrate == 0) {
+    // max is one bit per pixel
+    new_send_codec.maxBitrate = (static_cast<int>(send_codec->height) *
+        static_cast<int>(send_codec->width) *
+        static_cast<int>(send_codec->maxFramerate)) / 1000;
+    if (send_codec->startBitrate > new_send_codec.maxBitrate) {
+      // But if the user tries to set a higher start bit rate we will
+      // increase the max accordingly.
+      new_send_codec.maxBitrate = send_codec->startBitrate;
+    }
+  }
+
+  if (new_send_codec.startBitrate > new_send_codec.maxBitrate)
+    new_send_codec.startBitrate = new_send_codec.maxBitrate;
+
+  if (!reset_required) {
+    reset_required = RequiresEncoderReset(new_send_codec);
+  }
+
+  memcpy(&send_codec_, &new_send_codec, sizeof(send_codec_));
+
+  if (!reset_required) {
+    encoded_frame_callback_->SetPayloadType(send_codec_.plType);
+    return true;
+  }
+
+  // If encoder exists, will destroy it and create new one.
+  DeleteEncoder();
+  RTC_DCHECK_EQ(encoder_payload_type_, send_codec_.plType)
+      << "Encoder not registered for payload type " << send_codec_.plType;
+  ptr_encoder_.reset(
+      new VCMGenericEncoder(external_encoder_, encoder_rate_observer_,
+                            encoded_frame_callback_, internal_source_));
+  encoded_frame_callback_->SetPayloadType(send_codec_.plType);
+  encoded_frame_callback_->SetInternalSource(internal_source_);
+  if (ptr_encoder_->InitEncode(&send_codec_, number_of_cores_,
+                               max_payload_size_) < 0) {
+    LOG(LS_ERROR) << "Failed to initialize video encoder.";
+    DeleteEncoder();
+    return false;
+  }
+
+  // Intentionally don't check return value since the encoder registration
+  // shouldn't fail because the codec doesn't support changing the periodic key
+  // frame setting.
+  ptr_encoder_->SetPeriodicKeyFrames(periodic_key_frames_);
+
+  pending_encoder_reset_ = false;
+
+  return true;
+}
+
+bool VCMCodecDataBase::SendCodec(VideoCodec* current_send_codec) const {
+  if (!ptr_encoder_) {
+    return false;
+  }
+  memcpy(current_send_codec, &send_codec_, sizeof(VideoCodec));
+  return true;
+}
+
+VideoCodecType VCMCodecDataBase::SendCodec() const {
+  if (!ptr_encoder_) {
+    return kVideoCodecUnknown;
+  }
+  return send_codec_.codecType;
+}
+
+bool VCMCodecDataBase::DeregisterExternalEncoder(
+    uint8_t payload_type, bool* was_send_codec) {
+  assert(was_send_codec);
+  *was_send_codec = false;
+  if (encoder_payload_type_ != payload_type) {
+    return false;
+  }
+  if (send_codec_.plType == payload_type) {
+    // De-register as send codec if needed.
+    DeleteEncoder();
+    memset(&send_codec_, 0, sizeof(VideoCodec));
+    *was_send_codec = true;
+  }
+  encoder_payload_type_ = 0;
+  external_encoder_ = NULL;
+  internal_source_ = false;
+  return true;
+}
+
+void VCMCodecDataBase::RegisterExternalEncoder(
+    VideoEncoder* external_encoder,
+    uint8_t payload_type,
+    bool internal_source) {
+  // Since only one encoder can be used at a given time, only one external
+  // encoder can be registered/used.
+  external_encoder_ = external_encoder;
+  encoder_payload_type_ = payload_type;
+  internal_source_ = internal_source;
+  pending_encoder_reset_ = true;
+}
+
+bool VCMCodecDataBase::RequiresEncoderReset(const VideoCodec& new_send_codec) {
+  if (ptr_encoder_ == NULL) {
+    return true;
+  }
+
+  // Does not check startBitrate or maxFramerate
+  if (new_send_codec.codecType != send_codec_.codecType ||
+      strcmp(new_send_codec.plName, send_codec_.plName) != 0 ||
+      new_send_codec.plType != send_codec_.plType ||
+      new_send_codec.width != send_codec_.width ||
+      new_send_codec.height != send_codec_.height ||
+      new_send_codec.maxBitrate != send_codec_.maxBitrate ||
+      new_send_codec.minBitrate != send_codec_.minBitrate ||
+      new_send_codec.qpMax != send_codec_.qpMax ||
+      new_send_codec.numberOfSimulcastStreams !=
+          send_codec_.numberOfSimulcastStreams ||
+      new_send_codec.mode != send_codec_.mode ||
+      new_send_codec.extra_options != send_codec_.extra_options) {
+    return true;
+  }
+
+  switch (new_send_codec.codecType) {
+    case kVideoCodecVP8:
+      if (memcmp(&new_send_codec.codecSpecific.VP8,
+                 &send_codec_.codecSpecific.VP8,
+                 sizeof(new_send_codec.codecSpecific.VP8)) != 0) {
+        return true;
+      }
+      break;
+    case kVideoCodecVP9:
+      if (memcmp(&new_send_codec.codecSpecific.VP9,
+                 &send_codec_.codecSpecific.VP9,
+                 sizeof(new_send_codec.codecSpecific.VP9)) != 0) {
+        return true;
+      }
+      break;
+    case kVideoCodecH264:
+      if (memcmp(&new_send_codec.codecSpecific.H264,
+                 &send_codec_.codecSpecific.H264,
+                 sizeof(new_send_codec.codecSpecific.H264)) != 0) {
+        return true;
+      }
+      break;
+    case kVideoCodecGeneric:
+      break;
+    // Known codecs without payload-specifics
+    case kVideoCodecI420:
+    case kVideoCodecRED:
+    case kVideoCodecULPFEC:
+      break;
+    // Unknown codec type, reset just to be sure.
+    case kVideoCodecUnknown:
+      return true;
+  }
+
+  if (new_send_codec.numberOfSimulcastStreams > 0) {
+    for (unsigned char i = 0; i < new_send_codec.numberOfSimulcastStreams;
+         ++i) {
+      if (memcmp(&new_send_codec.simulcastStream[i],
+                 &send_codec_.simulcastStream[i],
+                 sizeof(new_send_codec.simulcastStream[i])) !=
+          0) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+VCMGenericEncoder* VCMCodecDataBase::GetEncoder() {
+  return ptr_encoder_.get();
+}
+
+bool VCMCodecDataBase::SetPeriodicKeyFrames(bool enable) {
+  periodic_key_frames_ = enable;
+  if (ptr_encoder_) {
+    return (ptr_encoder_->SetPeriodicKeyFrames(periodic_key_frames_) == 0);
+  }
+  return true;
+}
+
+void VCMCodecDataBase::ResetReceiver() {
+  ReleaseDecoder(ptr_decoder_);
+  ptr_decoder_ = NULL;
+  memset(&receive_codec_, 0, sizeof(VideoCodec));
+  while (!dec_map_.empty()) {
+    DecoderMap::iterator it = dec_map_.begin();
+    delete (*it).second;
+    dec_map_.erase(it);
+  }
+  while (!dec_external_map_.empty()) {
+    ExternalDecoderMap::iterator external_it = dec_external_map_.begin();
+    delete (*external_it).second;
+    dec_external_map_.erase(external_it);
+  }
+}
+
+bool VCMCodecDataBase::DeregisterExternalDecoder(uint8_t payload_type) {
+  ExternalDecoderMap::iterator it = dec_external_map_.find(payload_type);
+  if (it == dec_external_map_.end()) {
+    // Not found
+    return false;
+  }
+  // We can't use payload_type to check if the decoder is currently in use,
+  // because payload type may be out of date (e.g. before we decode the first
+  // frame after RegisterReceiveCodec)
+  if (ptr_decoder_ != NULL &&
+      &ptr_decoder_->_decoder == (*it).second->external_decoder_instance) {
+    // Release it if it was registered and in use.
+    ReleaseDecoder(ptr_decoder_);
+    ptr_decoder_ = NULL;
+  }
+  DeregisterReceiveCodec(payload_type);
+  delete (*it).second;
+  dec_external_map_.erase(it);
+  return true;
+}
+
+// Add the external encoder object to the list of external decoders.
+// Won't be registered as a receive codec until RegisterReceiveCodec is called.
+bool VCMCodecDataBase::RegisterExternalDecoder(
+    VideoDecoder* external_decoder,
+    uint8_t payload_type,
+    bool internal_render_timing) {
+  // Check if payload value already exists, if so  - erase old and insert new.
+  VCMExtDecoderMapItem* ext_decoder = new VCMExtDecoderMapItem(
+      external_decoder, payload_type, internal_render_timing);
+  if (!ext_decoder) {
+    return false;
+  }
+  DeregisterExternalDecoder(payload_type);
+  dec_external_map_[payload_type] = ext_decoder;
+  return true;
+}
+
+bool VCMCodecDataBase::DecoderRegistered() const {
+  return !dec_map_.empty();
+}
+
+bool VCMCodecDataBase::RegisterReceiveCodec(
+    const VideoCodec* receive_codec,
+    int number_of_cores,
+    bool require_key_frame) {
+  if (number_of_cores < 0) {
+    return false;
+  }
+  // Check if payload value already exists, if so  - erase old and insert new.
+  DeregisterReceiveCodec(receive_codec->plType);
+  if (receive_codec->codecType == kVideoCodecUnknown) {
+    return false;
+  }
+  VideoCodec* new_receive_codec = new VideoCodec(*receive_codec);
+  dec_map_[receive_codec->plType] = new VCMDecoderMapItem(new_receive_codec,
+                                                          number_of_cores,
+                                                          require_key_frame);
+  return true;
+}
+
+bool VCMCodecDataBase::DeregisterReceiveCodec(
+    uint8_t payload_type) {
+  DecoderMap::iterator it = dec_map_.find(payload_type);
+  if (it == dec_map_.end()) {
+    return false;
+  }
+  VCMDecoderMapItem* dec_item = (*it).second;
+  delete dec_item;
+  dec_map_.erase(it);
+  if (receive_codec_.plType == payload_type) {
+    // This codec is currently in use.
+    memset(&receive_codec_, 0, sizeof(VideoCodec));
+  }
+  return true;
+}
+
+bool VCMCodecDataBase::ReceiveCodec(VideoCodec* current_receive_codec) const {
+  assert(current_receive_codec);
+  if (!ptr_decoder_) {
+    return false;
+  }
+  memcpy(current_receive_codec, &receive_codec_, sizeof(VideoCodec));
+  return true;
+}
+
+VideoCodecType VCMCodecDataBase::ReceiveCodec() const {
+  if (!ptr_decoder_) {
+    return kVideoCodecUnknown;
+  }
+  return receive_codec_.codecType;
+}
+
+VCMGenericDecoder* VCMCodecDataBase::GetDecoder(
+    uint8_t payload_type, VCMDecodedFrameCallback* decoded_frame_callback) {
+  if (payload_type == receive_codec_.plType || payload_type == 0) {
+    return ptr_decoder_;
+  }
+  // Check for exisitng decoder, if exists - delete.
+  if (ptr_decoder_) {
+    ReleaseDecoder(ptr_decoder_);
+    ptr_decoder_ = NULL;
+    memset(&receive_codec_, 0, sizeof(VideoCodec));
+  }
+  ptr_decoder_ = CreateAndInitDecoder(payload_type, &receive_codec_);
+  if (!ptr_decoder_) {
+    return NULL;
+  }
+  VCMReceiveCallback* callback = decoded_frame_callback->UserReceiveCallback();
+  if (callback) callback->OnIncomingPayloadType(receive_codec_.plType);
+  if (ptr_decoder_->RegisterDecodeCompleteCallback(decoded_frame_callback)
+      < 0) {
+    ReleaseDecoder(ptr_decoder_);
+    ptr_decoder_ = NULL;
+    memset(&receive_codec_, 0, sizeof(VideoCodec));
+    return NULL;
+  }
+  return ptr_decoder_;
+}
+
+void VCMCodecDataBase::ReleaseDecoder(VCMGenericDecoder* decoder) const {
+  if (decoder) {
+    assert(&decoder->_decoder);
+    decoder->Release();
+    if (!decoder->External()) {
+      delete &decoder->_decoder;
+    }
+    delete decoder;
+  }
+}
+
+bool VCMCodecDataBase::SupportsRenderScheduling() const {
+  const VCMExtDecoderMapItem* ext_item = FindExternalDecoderItem(
+      receive_codec_.plType);
+  if (ext_item == nullptr)
+    return true;
+  return ext_item->internal_render_timing;
+}
+
+bool VCMCodecDataBase::MatchesCurrentResolution(int width, int height) const {
+  return send_codec_.width == width && send_codec_.height == height;
+}
+
+VCMGenericDecoder* VCMCodecDataBase::CreateAndInitDecoder(
+    uint8_t payload_type,
+    VideoCodec* new_codec) const {
+  assert(new_codec);
+  const VCMDecoderMapItem* decoder_item = FindDecoderItem(payload_type);
+  if (!decoder_item) {
+    LOG(LS_ERROR) << "Can't find a decoder associated with payload type: "
+                  << static_cast<int>(payload_type);
+    return NULL;
+  }
+  VCMGenericDecoder* ptr_decoder = NULL;
+  const VCMExtDecoderMapItem* external_dec_item =
+      FindExternalDecoderItem(payload_type);
+  if (external_dec_item) {
+    // External codec.
+    ptr_decoder = new VCMGenericDecoder(
+        *external_dec_item->external_decoder_instance, true);
+  } else {
+    // Create decoder.
+    ptr_decoder = CreateDecoder(decoder_item->settings->codecType);
+  }
+  if (!ptr_decoder)
+    return NULL;
+
+  if (ptr_decoder->InitDecode(decoder_item->settings.get(),
+                              decoder_item->number_of_cores) < 0) {
+    ReleaseDecoder(ptr_decoder);
+    return NULL;
+  }
+  memcpy(new_codec, decoder_item->settings.get(), sizeof(VideoCodec));
+  return ptr_decoder;
+}
+
+void VCMCodecDataBase::DeleteEncoder() {
+  if (!ptr_encoder_)
+    return;
+  ptr_encoder_->Release();
+  ptr_encoder_.reset();
+}
+
+VCMGenericDecoder* VCMCodecDataBase::CreateDecoder(VideoCodecType type) const {
+  switch (type) {
+#ifdef VIDEOCODEC_VP8
+    case kVideoCodecVP8:
+      return new VCMGenericDecoder(*(VP8Decoder::Create()));
+#endif
+#ifdef VIDEOCODEC_VP9
+    case kVideoCodecVP9:
+      return new VCMGenericDecoder(*(VP9Decoder::Create()));
+#endif
+#ifdef VIDEOCODEC_I420
+    case kVideoCodecI420:
+      return new VCMGenericDecoder(*(new I420Decoder));
+#endif
+#ifdef VIDEOCODEC_H264
+    case kVideoCodecH264:
+      if (H264Decoder::IsSupported()) {
+        return new VCMGenericDecoder(*(H264Decoder::Create()));
+      }
+      break;
+#endif
+    default:
+      break;
+  }
+  LOG(LS_WARNING) << "No internal decoder of this type exists.";
+  return NULL;
+}
+
+const VCMDecoderMapItem* VCMCodecDataBase::FindDecoderItem(
+    uint8_t payload_type) const {
+  DecoderMap::const_iterator it = dec_map_.find(payload_type);
+  if (it != dec_map_.end()) {
+    return (*it).second;
+  }
+  return NULL;
+}
+
+const VCMExtDecoderMapItem* VCMCodecDataBase::FindExternalDecoderItem(
+    uint8_t payload_type) const {
+  ExternalDecoderMap::const_iterator it = dec_external_map_.find(payload_type);
+  if (it != dec_external_map_.end()) {
+    return (*it).second;
+  }
+  return NULL;
+}
+}  // namespace webrtc