The Tor Browser: content/media/fmp4/PlatformDecoderModule.h@97036ab72558 (annotated)

content/media/fmp4/PlatformDecoderModule.h@97036ab72558 (annotated)

content/media/fmp4/PlatformDecoderModule.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- 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

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content/media/fmp4/PlatformDecoderModule.h@97036ab72558 (annotated)

content/media/fmp4/PlatformDecoderModule.h