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 enum Status { 24 kOk, // Everything went as planned. 25 kNotEnoughData, // Not enough data to produce a video frame. 26 kDecodeError, // Decoding error happened. 27 kDecryptError // Decrypting error happened. 28 }; 29 30 VideoDecoder(); 31 virtual ~VideoDecoder(); 32 33 // Initializes a VideoDecoder with the given |config|, executing the 34 // |status_cb| upon completion. 35 // 36 // Note: 37 // 1) The VideoDecoder will be reinitialized if it was initialized before. 38 // Upon reinitialization, all internal buffered frames will be dropped. 39 // 2) This method should not be called during pending decode, reset or stop. 40 // 3) No VideoDecoder calls except for Stop() should be made before 41 // |status_cb| is executed. 42 virtual void Initialize(const VideoDecoderConfig& config, 43 const PipelineStatusCB& status_cb) = 0; 44 45 // Requests a |buffer| to be decoded. The status of the decoder and decoded 46 // frame are returned via the provided callback. Only one decode may be in 47 // flight at any given time. 48 // 49 // Implementations guarantee that the callback will not be called from within 50 // this method. 51 // 52 // If the returned status is kOk: 53 // - Non-EOS (end of stream) frame contains decoded video data. 54 // - EOS frame indicates the end of the stream. 55 // - NULL frame indicates an aborted decode. This can happen if Reset() or 56 // Stop() is called during the decoding process. 57 // Otherwise the returned frame must be NULL. 58 typedef base::Callback<void(Status, 59 const scoped_refptr<VideoFrame>&)> DecodeCB; 60 virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer, 61 const DecodeCB& decode_cb) = 0; 62 63 // Resets decoder state, fulfilling all pending DecodeCB and dropping extra 64 // queued decoded data. After this call, the decoder is back to an initialized 65 // clean state. 66 // Note: No VideoDecoder calls should be made before |closure| is executed. 67 virtual void Reset(const base::Closure& closure) = 0; 68 69 // Stops decoder, fires any pending callbacks and sets the decoder to an 70 // uninitialized state. A VideoDecoder cannot be re-initialized after it has 71 // been stopped. 72 // Note that if Initialize() has been called, Stop() must be called and 73 // complete before deleting the decoder. 74 virtual void Stop(const base::Closure& closure) = 0; 75 76 // Returns true if the output format has an alpha channel. Most formats do not 77 // have alpha so the default is false. Override and return true for decoders 78 // that return formats with an alpha channel. 79 virtual bool HasAlpha() const; 80 81 // Returns true if the decoder needs bitstream conversion before decoding. 82 virtual bool NeedsBitstreamConversion() const; 83 84 // Returns true if the decoder currently has the ability to decode and return 85 // a VideoFrame. Most implementations can allocate a new VideoFrame and hence 86 // this will always return true. Override and return false for decoders that 87 // use a fixed set of VideoFrames for decoding. 88 virtual bool CanReadWithoutStalling() const; 89 90 private: 91 DISALLOW_COPY_AND_ASSIGN(VideoDecoder); 92 }; 93 94 } // namespace media 95 96 #endif // MEDIA_BASE_VIDEO_DECODER_H_ 97
