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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