media/filters/decoder_selector.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_FILTERS_DECODER_SELECTOR_H_
   6 #define MEDIA_FILTERS_DECODER_SELECTOR_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_vector.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "media/base/decryptor.h"
  13 #include "media/base/demuxer_stream.h"
  14 #include "media/base/pipeline_status.h"
  15 #include "media/filters/decoder_stream_traits.h"
  16
  17 namespace base {
  18 class SingleThreadTaskRunner;
  19 }
  20
  21 namespace media {
  22
  23 class DecoderBuffer;
  24 class DecryptingDemuxerStream;
  25 class Decryptor;
  26
  27 // DecoderSelector (creates if necessary and) initializes the proper
  28 // Decoder for a given DemuxerStream. If the given DemuxerStream is
  29 // encrypted, a DecryptingDemuxerStream may also be created.
  30 // The template parameter |StreamType| is the type of stream we will be
  31 // selecting a decoder for.
  32 template<DemuxerStream::Type StreamType>
  33 class MEDIA_EXPORT DecoderSelector {
  34  public:
  35   typedef DecoderStreamTraits<StreamType> StreamTraits;
  36   typedef typename StreamTraits::DecoderType Decoder;
  37
  38   // Indicates completion of Decoder selection.
  39   // - First parameter: The initialized Decoder. If it's set to NULL, then
  40   // Decoder initialization failed.
  41   // - Second parameter: The initialized DecryptingDemuxerStream. If it's not
  42   // NULL, then a DecryptingDemuxerStream is created and initialized to do
  43   // decryption for the initialized Decoder.
  44   // Note: The caller owns selected Decoder and DecryptingDemuxerStream.
  45   // The caller should call DecryptingDemuxerStream::Reset() before
  46   // calling Decoder::Reset() to release any pending decryption or read.
  47   typedef base::Callback<
  48       void(scoped_ptr<Decoder>,
  49            scoped_ptr<DecryptingDemuxerStream>)>
  50       SelectDecoderCB;
  51
  52   // |decoders| contains the Decoders to use when initializing.
  53   DecoderSelector(
  54       const scoped_refptr<base::SingleThreadTaskRunner>& message_loop,
  55       ScopedVector<Decoder> decoders);
  56
  57   // Aborts pending Decoder selection and fires |select_decoder_cb| with
  58   // NULL and NULL immediately if it's pending.
  59   ~DecoderSelector();
  60
  61   // Initializes and selects the first Decoder that can decode the |stream|.
  62   // The selected Decoder (and DecryptingDemuxerStream) is returned via
  63   // the |select_decoder_cb|.
  64   // Notes:
  65   // 1. This must not be called again before |select_decoder_cb| is run.
  66   // 2. Decoders that fail to initialize will be deleted. Future calls will
  67   //    select from the decoders following the decoder that was last returned.
  68   // 3. |set_decryptor_ready_cb| is optional. If |set_decryptor_ready_cb| is
  69   //    null, no decryptor will be available to perform decryption.
  70   void SelectDecoder(DemuxerStream* stream,
  71                      const SetDecryptorReadyCB& set_decryptor_ready_cb,
  72                      const SelectDecoderCB& select_decoder_cb,
  73                      const typename Decoder::OutputCB& output_cb);
  74
  75  private:
  76   void DecryptingDecoderInitDone(PipelineStatus status);
  77   void DecryptingDemuxerStreamInitDone(PipelineStatus status);
  78   void InitializeDecoder();
  79   void DecoderInitDone(PipelineStatus status);
  80   void ReturnNullDecoder();
  81
  82   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  83   ScopedVector<Decoder> decoders_;
  84
  85   DemuxerStream* input_stream_;
  86   SetDecryptorReadyCB set_decryptor_ready_cb_;
  87   SelectDecoderCB select_decoder_cb_;
  88   typename Decoder::OutputCB output_cb_;
  89
  90   scoped_ptr<Decoder> decoder_;
  91   scoped_ptr<DecryptingDemuxerStream> decrypted_stream_;
  92
  93   // NOTE: Weak pointers must be invalidated before all other member variables.
  94   base::WeakPtrFactory<DecoderSelector> weak_ptr_factory_;
  95
  96   DISALLOW_IMPLICIT_CONSTRUCTORS(DecoderSelector);
  97 };
  98
  99 typedef DecoderSelector<DemuxerStream::VIDEO> VideoDecoderSelector;
 100 typedef DecoderSelector<DemuxerStream::AUDIO> AudioDecoderSelector;
 101
 102 }  // namespace media
 103
 104 #endif  // MEDIA_FILTERS_DECODER_SELECTOR_H_