Move VideoDecoder::Create() logic to separate internal video decoder factory

webrtc/video/video_decoder.cc

-/*
- *  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 "webrtc/video_decoder.h"
-
-#include "webrtc/base/checks.h"
-#include "webrtc/base/logging.h"
-#include "webrtc/modules/video_coding/codecs/h264/include/h264.h"
-#include "webrtc/modules/video_coding/codecs/vp8/include/vp8.h"
-#include "webrtc/modules/video_coding/codecs/vp9/include/vp9.h"
-
-namespace webrtc {
-VideoDecoder* VideoDecoder::Create(VideoDecoder::DecoderType codec_type) {
-  switch (codec_type) {
-    case kH264:
-      if (!H264Decoder::IsSupported()) {
-        // This could happen in a software-fallback for a codec type only
-        // supported externally (e.g. H.264 on iOS or Android) or in current
-        // usage in WebRtcVideoEngine2 if the external decoder fails to be
-        // created.
-        LOG(LS_ERROR) << "Unable to create an H.264 decoder fallback. "
-                      << "Decoding of this stream will be broken.";
-        return new NullVideoDecoder();
-      }
-      return H264Decoder::Create();
-    case kVp8:
-      return VP8Decoder::Create();
-    case kVp9:
-      RTC_DCHECK(VP9Decoder::IsSupported());
-      return VP9Decoder::Create();
-    case kUnsupportedCodec:
-      LOG(LS_ERROR) << "Creating NullVideoDecoder for unsupported codec.";
-      return new NullVideoDecoder();
-  }
-  RTC_NOTREACHED();
-  return nullptr;
-}
-
-NullVideoDecoder::NullVideoDecoder() {}
-
-int32_t NullVideoDecoder::InitDecode(const VideoCodec* codec_settings,
-                                     int32_t number_of_cores) {
-  LOG(LS_ERROR) << "Can't initialize NullVideoDecoder.";
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int32_t NullVideoDecoder::Decode(const EncodedImage& input_image,
-    bool missing_frames,
-    const RTPFragmentationHeader* fragmentation,
-    const CodecSpecificInfo* codec_specific_info,
-    int64_t render_time_ms) {
-  LOG(LS_ERROR) << "The NullVideoDecoder doesn't support decoding.";
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int32_t NullVideoDecoder::RegisterDecodeCompleteCallback(
-    DecodedImageCallback* callback) {
-  LOG(LS_ERROR)
-      << "Can't register decode complete callback on NullVideoDecoder.";
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int32_t NullVideoDecoder::Release() {
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-const char* NullVideoDecoder::ImplementationName() const {
-  return "NullVideoDecoder";
-}
-
-}  // namespace webrtc