1 // Copyright (c) 2012 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_BASE_VIDEO_DECODER_H_ 6 #define MEDIA_BASE_VIDEO_DECODER_H_ 7 8 #include "base/callback.h" 9 #include "base/memory/ref_counted.h" 10 #include "media/base/media_export.h" 11 #include "media/base/pipeline_status.h" 12 #include "ui/gfx/size.h" 13 14 namespace media { 15 16 class DecoderBuffer; 17 class VideoDecoderConfig; 18 class VideoFrame; 19 20 class MEDIA_EXPORT VideoDecoder { 21 public: 22 // Status codes for decode operations on VideoDecoder. 23 // TODO(rileya): Now that both AudioDecoder and VideoDecoder Status enums 24 // match, break them into a decoder_status.h. 25 enum Status { 26 kOk, // Everything went as planned. 27 kAborted, // Decode was aborted as a result of Reset() being called. 28 kDecodeError, // Decoding error happened. 29 kDecryptError // Decrypting error happened. 30 }; 31 32 // Callback for VideoDecoder to return a decoded frame whenever it becomes 33 // available. Only non-EOS frames should be returned via this callback. 34 typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> OutputCB; 35 36 // Callback type for Decode(). Called after the decoder has completed decoding 37 // corresponding DecoderBuffer, indicating that it's ready to accept another 38 // buffer to decode. 39 typedef base::Callback<void(Status status)> DecodeCB; 40 41 VideoDecoder(); 42 virtual ~VideoDecoder(); 43 44 // Initializes a VideoDecoder with the given |config|, executing the 45 // |status_cb| upon completion. |output_cb| is called for each output frame 46 // decoded by Decode(). 47 // 48 // Note: 49 // 1) The VideoDecoder will be reinitialized if it was initialized before. 50 // Upon reinitialization, all internal buffered frames will be dropped. 51 // 2) This method should not be called during pending decode, reset or stop. 52 // 3) No VideoDecoder calls except for Stop() should be made before 53 // |status_cb| is executed. 54 virtual void Initialize(const VideoDecoderConfig& config, 55 bool low_delay, 56 const PipelineStatusCB& status_cb, 57 const OutputCB& output_cb) = 0; 58 59 // Requests a |buffer| to be decoded. The status of the decoder and decoded 60 // frame are returned via the provided callback. Some decoders may allow 61 // decoding multiple buffers in parallel. Callers should call 62 // GetMaxDecodeRequests() to get number of buffers that may be decoded in 63 // parallel. Decoder must call |decode_cb| in the same order in which Decode() 64 // is called. 65 // 66 // Implementations guarantee that the callback will not be called from within 67 // this method and that |decode_cb| will not be blocked on the following 68 // Decode() calls (i.e. |decode_cb| will be called even Decode() is never 69 // called again). 70 // 71 // After decoding is finished the decoder calls |output_cb| specified in 72 // Initialize() for each decoded frame. |output_cb| may be called before or 73 // after |decode_cb|. 74 // 75 // If |buffer| is an EOS buffer then the decoder must be flushed, i.e. 76 // |output_cb| must be called for each frame pending in the queue and 77 // |decode_cb| must be called after that. 78 virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer, 79 const DecodeCB& decode_cb) = 0; 80 81 // Resets decoder state. All pending Decode() requests will be finished or 82 // aborted before |closure| is called. 83 // Note: No VideoDecoder calls should be made before |closure| is executed. 84 virtual void Reset(const base::Closure& closure) = 0; 85 86 // Stops decoder, fires any pending callbacks and sets the decoder to an 87 // uninitialized state. A VideoDecoder cannot be re-initialized after it has 88 // been stopped. 89 // Note that if Initialize() is pending or has finished successfully, Stop() 90 // must be called before destructing the decoder. 91 virtual void Stop() = 0; 92 93 // Returns true if the decoder needs bitstream conversion before decoding. 94 virtual bool NeedsBitstreamConversion() const; 95 96 // Returns true if the decoder currently has the ability to decode and return 97 // a VideoFrame. Most implementations can allocate a new VideoFrame and hence 98 // this will always return true. Override and return false for decoders that 99 // use a fixed set of VideoFrames for decoding. 100 virtual bool CanReadWithoutStalling() const; 101 102 // Returns maximum number of parallel decode requests. 103 virtual int GetMaxDecodeRequests() const; 104 105 private: 106 DISALLOW_COPY_AND_ASSIGN(VideoDecoder); 107 }; 108 109 } // namespace media 110 111 #endif // MEDIA_BASE_VIDEO_DECODER_H_ 112
