1 files changed, 110 insertions, 0 deletions
diff --git a/dom/media/directshow/DirectShowReader.h b/dom/media/directshow/DirectShowReader.h
new file mode 100644
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+++ b/dom/media/directshow/DirectShowReader.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#if !defined(DirectShowReader_h_)
+#define DirectShowReader_h_
+
+#include "windows.h" // HRESULT, DWORD
+#include "MediaDecoderReader.h"
+#include "MediaResource.h"
+#include "mozilla/RefPtr.h"
+#include "MP3FrameParser.h"
+
+// Add the graph to the Running Object Table so that we can connect
+// to this graph with GraphEdit/GraphStudio. Note: on Vista and up you must
+// also regsvr32 proppage.dll from the Windows SDK.
+// See: http://msdn.microsoft.com/en-us/library/ms787252(VS.85).aspx
+// #define DIRECTSHOW_REGISTER_GRAPH
+
+struct IGraphBuilder;
+struct IMediaControl;
+struct IMediaSeeking;
+
+namespace mozilla {
+
+class AudioSinkFilter;
+class SourceFilter;
+
+// Decoder backend for decoding MP3 using DirectShow. DirectShow operates as
+// a filter graph. The basic design of the DirectShowReader is that we have
+// a SourceFilter that wraps the MediaResource that connects to the
+// MP3 decoder filter. The MP3 decoder filter "pulls" data as it requires it
+// downstream on its own thread. When the MP3 decoder has produced a block of
+// decoded samples, its thread calls downstream into our AudioSinkFilter,
+// passing the decoded buffer in. The AudioSinkFilter inserts the samples into
+// a SampleSink object. The SampleSink blocks the MP3 decoder's thread until
+// the decode thread calls DecodeAudioData(), whereupon the SampleSink
+// releases the decoded samples to the decode thread, and unblocks the MP3
+// decoder's thread. The MP3 decoder can then request more data from the
+// SourceFilter, and decode more data. If the decode thread calls
+// DecodeAudioData() and there's no decoded samples waiting to be extracted
+// in the SampleSink, the SampleSink blocks the decode thread until the MP3
+// decoder produces a decoded sample.
+class DirectShowReader : public MediaDecoderReader
+{
+public:
+  DirectShowReader(AbstractMediaDecoder* aDecoder);
+
+  virtual ~DirectShowReader();
+
+  bool DecodeAudioData() override;
+  bool DecodeVideoFrame(bool &aKeyframeSkip,
+                        int64_t aTimeThreshold) override;
+
+  nsresult ReadMetadata(MediaInfo* aInfo,
+                        MetadataTags** aTags) override;
+
+  RefPtr<SeekPromise>
+  Seek(SeekTarget aTarget, int64_t aEndTime) override;
+
+  static const GUID CLSID_MPEG_LAYER_3_DECODER_FILTER;
+
+private:
+  // Notifies the filter graph that playback is complete. aStatus is
+  // the code to send to the filter graph. Always returns false, so
+  // that we can just "return Finish()" from DecodeAudioData().
+  bool Finish(HRESULT aStatus);
+
+  nsresult SeekInternal(int64_t aTime);
+
+  // DirectShow filter graph, and associated playback and seeking
+  // control interfaces.
+  RefPtr<IGraphBuilder> mGraph;
+  RefPtr<IMediaControl> mControl;
+  RefPtr<IMediaSeeking> mMediaSeeking;
+
+  // Wraps the MediaResource, and feeds undecoded data into the filter graph.
+  RefPtr<SourceFilter> mSourceFilter;
+
+  // Sits at the end of the graph, removing decoded samples from the graph.
+  // The graph will block while this is blocked, i.e. it will pause decoding.
+  RefPtr<AudioSinkFilter> mAudioSinkFilter;
+
+  // Some MP3s are variable bitrate, so DirectShow's duration estimation
+  // can make its duration estimation based on the wrong bitrate. So we parse
+  // the MP3 frames to get a more accuate estimate of the duration.
+  MP3FrameParser mMP3FrameParser;
+
+#ifdef DIRECTSHOW_REGISTER_GRAPH
+  // Used to add/remove the filter graph to the Running Object Table. You can
+  // connect GraphEdit/GraphStudio to the graph to observe and/or debug its
+  // topology and state.
+  DWORD mRotRegister;
+#endif
+
+  // Number of channels in the audio stream.
+  uint32_t mNumChannels;
+
+  // Samples per second in the audio stream.
+  uint32_t mAudioRate;
+
+  // Number of bytes per sample. Can be either 1 or 2.
+  uint32_t mBytesPerSample;
+};
+
+} // namespace mozilla
+
+#endif