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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(PlatformDecoderModule_h_)

 #define PlatformDecoderModule_h_

 #include "MediaDecoderReader.h"

 #include "mozilla/layers/LayersTypes.h"

 #include "nsTArray.h"

 #include "mozilla/RefPtr.h"

 #include <queue>

 namespace mp4_demuxer {

 class VideoDecoderConfig;

 class AudioDecoderConfig;

 struct MP4Sample;

 }

 class nsIThreadPool;

 namespace mozilla {

 namespace layers {

 class ImageContainer;

 }

 class MediaDataDecoder;

 class MediaDataDecoderCallback;

 class MediaInputQueue;

 class MediaTaskQueue;

 typedef int64_t Microseconds;

 // The PlatformDecoderModule interface is used by the MP4Reader to abstract

 // access to the H264 and AAC decoders provided by various platforms. It

 // may be extended to support other codecs in future. Each platform (Windows,

 // MacOSX, Linux, B2G etc) must implement a PlatformDecoderModule to provide

 // access to its decoders in order to get decompressed H.264/AAC from the

 // MP4Reader.

 //

 // Video decoding is asynchronous, and should be performed on the task queue

 // provided if the underlying platform isn't already exposing an async API.

 //

 // Platforms that don't have a corresponding PlatformDecoderModule won't be

 // able to play the H.264/AAC data output by the MP4Reader. In practice this

 // means that we won't have fragmented MP4 supported in Media Source

 // Extensions.

 //

 // A cross-platform decoder module that discards input and produces "blank"

 // output samples exists for testing, and is created when the pref

 // "media.fragmented-mp4.use-blank-decoder" is true.

 class PlatformDecoderModule {

 public:

   // Call on the main thread to initialize the static state

   // needed by Create().

   static void Init();

   // Factory method that creates the appropriate PlatformDecoderModule for

   // the platform we're running on. Caller is responsible for deleting this

   // instance. It's expected that there will be multiple

   // PlatformDecoderModules alive at the same time. There is one

   // PlatformDecoderModule created per MP4Reader.

   // This is called on the decode thread.

   static PlatformDecoderModule* Create();

   // Called to shutdown the decoder module and cleanup state. This should

   // block until shutdown is complete. This is called after Shutdown() has

   // been called on all MediaDataDecoders created from this

   // PlatformDecoderModule.

   // Called on the main thread only.

   virtual nsresult Shutdown() = 0;

   // Creates an H.264 decoder. The layers backend is passed in so that

   // decoders can determine whether hardware accelerated decoding can be used.

   // Asynchronous decoding of video should be done in runnables dispatched

   // to aVideoTaskQueue. If the task queue isn't needed, the decoder should

   // not hold a reference to it.

   // Output and errors should be returned to the reader via aCallback.

   // On Windows the task queue's threads in have MSCOM initialized with

   // COINIT_MULTITHREADED.

   // Returns nullptr if the decoder can't be created.

   // It is safe to store a reference to aConfig.

   // Called on decode thread.

   virtual MediaDataDecoder* CreateH264Decoder(const mp4_demuxer::VideoDecoderConfig& aConfig,

                                               layers::LayersBackend aLayersBackend,

                                               layers::ImageContainer* aImageContainer,

                                               MediaTaskQueue* aVideoTaskQueue,

                                               MediaDataDecoderCallback* aCallback) = 0;

   // Creates an AAC decoder with the specified properties.

   // Asynchronous decoding of audio should be done in runnables dispatched to

   // aAudioTaskQueue. If the task queue isn't needed, the decoder should

   // not hold a reference to it.

   // Output and errors should be returned to the reader via aCallback.

   // Returns nullptr if the decoder can't be created.

   // On Windows the task queue's threads in have MSCOM initialized with

   // COINIT_MULTITHREADED.

   // It is safe to store a reference to aConfig.

   // Called on decode thread.

   virtual MediaDataDecoder* CreateAACDecoder(const mp4_demuxer::AudioDecoderConfig& aConfig,

                                              MediaTaskQueue* aAudioTaskQueue,

                                              MediaDataDecoderCallback* aCallback) = 0;

   virtual ~PlatformDecoderModule() {}

 protected:

   PlatformDecoderModule() {}

   // Caches pref media.fragmented-mp4.use-blank-decoder

   static bool sUseBlankDecoder;

   static bool sFFmpegDecoderEnabled;

 };

 // A callback used by MediaDataDecoder to return output/errors to the

 // MP4Reader. Implementation is threadsafe, and can be called on any thread.

 class MediaDataDecoderCallback {

 public:

   virtual ~MediaDataDecoderCallback() {}

   // Called by MediaDataDecoder when a sample has been decoded. Callee is

   // responsibile for deleting aData.

   virtual void Output(MediaData* aData) = 0;

   // Denotes an error in the decoding process. The reader will stop calling

   // the decoder.

   virtual void Error() = 0;

   // Denotes that the last input sample has been inserted into the decoder,

   // and no more output can be produced unless more input is sent.

   virtual void InputExhausted() = 0;

 };

 // MediaDataDecoder is the interface exposed by decoders created by the

 // PlatformDecoderModule's Create*Decoder() functions. The type of

 // media data that the decoder accepts as valid input and produces as

 // output is determined when the MediaDataDecoder is created.

 //

 // All functions must be threadsafe, and be able to be called on an

 // arbitrary thread.

 //

 // Decoding is done asynchronously. Any async work can be done on the

 // MediaTaskQueue passed into the PlatformDecoderModules's Create*Decoder()

 // function. This may not be necessary for platforms with async APIs

 // for decoding.

 class MediaDataDecoder {

 protected:

   virtual ~MediaDataDecoder() {};

 public:

   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaDataDecoder)

   // Initialize the decoder. The decoder should be ready to decode after

   // this returns. The decoder should do any initialization here, rather

   // than in its constructor or PlatformDecoderModule::Create*Decoder(),

   // so that if the MP4Reader needs to shutdown during initialization,

   // it can call Shutdown() to cancel this operation. Any initialization

   // that requires blocking the calling thread in this function *must*

   // be done here so that it can be canceled by calling Shutdown()!

   virtual nsresult Init() = 0;

   // Inserts a sample into the decoder's decode pipeline. The decoder must

   // delete the sample once its been decoded. If Input() returns an error,

   // aSample will be deleted by the caller.

   virtual nsresult Input(mp4_demuxer::MP4Sample* aSample) = 0;

   // Causes all samples in the decoding pipeline to be discarded. When

   // this function returns, the decoder must be ready to accept new input

   // for decoding. This function is called when the demuxer seeks, before

   // decoding resumes after the seek.

   // While the reader calls Flush(), it ignores all output sent to it;

   // it is safe (but pointless) to send output while Flush is called.

   // The MP4Reader will not call Input() while it's calling Flush().

   virtual nsresult Flush() = 0;

   // Causes all complete samples in the pipeline that can be decoded to be

   // output. If the decoder can't produce samples from the current output,

   // it drops the input samples. The decoder may be holding onto samples

   // that are required to decode samples that it expects to get in future.

   // This is called when the demuxer reaches end of stream.

   // The MP4Reader will not call Input() while it's calling Drain().

   virtual nsresult Drain() = 0;

   // Cancels all init/input/drain operations, and shuts down the

   // decoder. The platform decoder should clean up any resources it's using

   // and release memory etc. Shutdown() must block until the decoder has

   // completed shutdown. The reader calls Flush() before calling Shutdown().

   // The reader will delete the decoder once Shutdown() returns.

   // The MediaDataDecoderCallback *must* not be called after Shutdown() has

   // returned.

   virtual nsresult Shutdown() = 0;

 };

 } // namespace mozilla

 #endif