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 H264_DECODER_H_ 6 #define H264_DECODER_H_ 7 8 #include <stddef.h> 9 #include <stdint.h> 10 11 #include <memory> 12 #include <vector> 13 14 #include "base/macros.h" 15 #include "base/memory/ref_counted.h" 16 #include "accelerated_video_decoder.h" 17 #include "h264_dpb.h" 18 #include "h264_parser.h" 19 #include "size.h" 20 21 namespace media { 22 23 // Clients of this class are expected to pass H264 Annex-B byte stream 24 // and are expected to provide an implementation of H264Accelerator for 25 // offloading final steps of the decoding process. 26 // 27 // This class must be created, called and destroyed on a single thread, and 28 // does nothing internally on any other thread. 29 class H264Decoder : public AcceleratedVideoDecoder { 30 public: 31 class H264Accelerator { 32 public: 33 H264Accelerator(); 34 virtual ~H264Accelerator(); 35 36 // Create a new H264Picture that the decoder client can use for decoding 37 // and pass back to this accelerator for decoding or reference. 38 // When the picture is no longer needed by decoder, it will just drop 39 // its reference to it, and it may do so at any time. 40 // Note that this may return nullptr if accelerator is not able to provide 41 // any new pictures at given time. The decoder is expected to handle 42 // this situation as normal and return from Decode() with kRanOutOfSurfaces. 43 virtual scoped_refptr<H264Picture> CreateH264Picture() = 0; 44 45 // Submit metadata for the current frame, providing the current |sps| and 46 // |pps| for it, |dpb| has to contain all the pictures in DPB for current 47 // frame, and |ref_pic_p0/b0/b1| as specified in the H264 spec. Note that 48 // depending on the frame type, either p0, or b0 and b1 are used. |pic| 49 // contains information about the picture for the current frame. 50 // Note that this does not run decode in the accelerator and the decoder 51 // is expected to follow this call with one or more SubmitSlice() calls 52 // before calling SubmitDecode(). 53 // Return true if successful. 54 virtual bool SubmitFrameMetadata(const H264SPS* sps, 55 const H264PPS* pps, 56 const H264DPB& dpb, 57 const H264Picture::Vector& ref_pic_listp0, 58 const H264Picture::Vector& ref_pic_listb0, 59 const H264Picture::Vector& ref_pic_listb1, 60 const scoped_refptr<H264Picture>& pic) = 0; 61 62 // Submit one slice for the current frame, passing the current |pps| and 63 // |pic| (same as in SubmitFrameMetadata()), the parsed header for the 64 // current slice in |slice_hdr|, and the reordered |ref_pic_listX|, 65 // as per H264 spec. 66 // |data| pointing to the full slice (including the unparsed header| of 67 // |size| in bytes. 68 // This must be called one or more times per frame, before SubmitDecode(). 69 // Note that |data| does not have to remain valid after this call returns. 70 // Return true if successful. 71 virtual bool SubmitSlice(const H264PPS* pps, 72 const H264SliceHeader* slice_hdr, 73 const H264Picture::Vector& ref_pic_list0, 74 const H264Picture::Vector& ref_pic_list1, 75 const scoped_refptr<H264Picture>& pic, 76 const uint8_t* data, 77 size_t size) = 0; 78 79 // Execute the decode in hardware for |pic|, using all the slices and 80 // metadata submitted via SubmitFrameMetadata() and SubmitSlice() since 81 // the previous call to SubmitDecode(). 82 // Return true if successful. 83 virtual bool SubmitDecode(const scoped_refptr<H264Picture>& pic) = 0; 84 85 // Schedule output (display) of |pic|. Note that returning from this 86 // method does not mean that |pic| has already been outputted (displayed), 87 // but guarantees that all pictures will be outputted in the same order 88 // as this method was called for them. Decoder may drop its reference 89 // to |pic| after calling this method. 90 // Return true if successful. 91 virtual bool OutputPicture(const scoped_refptr<H264Picture>& pic) = 0; 92 93 // Reset any current state that may be cached in the accelerator, dropping 94 // any cached parameters/slices that have not been committed yet. 95 virtual void Reset() = 0; 96 97 private: 98 DISALLOW_COPY_AND_ASSIGN(H264Accelerator); 99 }; 100 101 H264Decoder(H264Accelerator* accelerator); 102 ~H264Decoder() override; 103 104 // AcceleratedVideoDecoder implementation. 105 bool Flush() override WARN_UNUSED_RESULT; 106 void Reset() override; 107 void SetStream(const uint8_t* ptr, size_t size) override; 108 DecodeResult Decode() override WARN_UNUSED_RESULT; 109 Size GetPicSize() const override; 110 size_t GetRequiredNumOfPictures() const override; 111 112 private: 113 // We need to keep at most kDPBMaxSize pictures in DPB for 114 // reference/to display later and an additional one for the one currently 115 // being decoded. We also ask for some additional ones since VDA needs 116 // to accumulate a few ready-to-output pictures before it actually starts 117 // displaying and giving them back. +2 instead of +1 because of subjective 118 // smoothness improvement during testing. 119 enum { 120 // TODO(johnylin): see if we could get rid of kMaxVideoFrames. 121 kMaxVideoFrames = 4, 122 kPicsInPipeline = kMaxVideoFrames + 2, 123 kMaxNumReqPictures = H264DPB::kDPBMaxSize + kPicsInPipeline, 124 }; 125 126 // Internal state of the decoder. 127 enum State { 128 kNeedStreamMetadata, // After initialization, need an SPS. 129 kDecoding, // Ready to decode from any point. 130 kAfterReset, // After Reset(), need a resume point. 131 kError, // Error in decode, can't continue. 132 }; 133 134 // Process H264 stream structures. 135 bool ProcessSPS(int sps_id, bool* need_new_buffers); 136 // Process current slice header to discover if we need to start a new picture, 137 // finishing up the current one. 138 bool PreprocessCurrentSlice(); 139 // Process current slice as a slice of the current picture. 140 bool ProcessCurrentSlice(); 141 142 // Return true if we need to start a new picture. 143 bool IsNewPrimaryCodedPicture(const H264SliceHeader* slice_hdr) const; 144 145 // Initialize the current picture according to data in |slice_hdr|. 146 bool InitCurrPicture(const H264SliceHeader* slice_hdr); 147 148 // Initialize |pic| as a "non-existing" picture (see spec) with |frame_num|, 149 // to be used for frame gap concealment. 150 bool InitNonexistingPicture(scoped_refptr<H264Picture> pic, int frame_num); 151 152 // Calculate picture order counts for |pic| on initialization 153 // of a new frame (see spec). 154 bool CalculatePicOrderCounts(scoped_refptr<H264Picture> pic); 155 156 // Update PicNum values in pictures stored in DPB on creation of 157 // a picture with |frame_num|. 158 void UpdatePicNums(int frame_num); 159 160 bool UpdateMaxNumReorderFrames(const H264SPS* sps); 161 162 // Prepare reference picture lists for the current frame. 163 void PrepareRefPicLists(const H264SliceHeader* slice_hdr); 164 // Prepare reference picture lists for the given slice. 165 bool ModifyReferencePicLists(const H264SliceHeader* slice_hdr, 166 H264Picture::Vector* ref_pic_list0, 167 H264Picture::Vector* ref_pic_list1); 168 169 // Construct initial reference picture lists for use in decoding of 170 // P and B pictures (see 8.2.4 in spec). 171 void ConstructReferencePicListsP(const H264SliceHeader* slice_hdr); 172 void ConstructReferencePicListsB(const H264SliceHeader* slice_hdr); 173 174 // Helper functions for reference list construction, per spec. 175 int PicNumF(const scoped_refptr<H264Picture>& pic); 176 int LongTermPicNumF(const scoped_refptr<H264Picture>& pic); 177 178 // Perform the reference picture lists' modification (reordering), as 179 // specified in spec (8.2.4). 180 // 181 // |list| indicates list number and should be either 0 or 1. 182 bool ModifyReferencePicList(const H264SliceHeader* slice_hdr, 183 int list, 184 H264Picture::Vector* ref_pic_listx); 185 186 // Perform reference picture memory management operations (marking/unmarking 187 // of reference pictures, long term picture management, discarding, etc.). 188 // See 8.2.5 in spec. 189 bool HandleMemoryManagementOps(scoped_refptr<H264Picture> pic); 190 bool ReferencePictureMarking(scoped_refptr<H264Picture> pic); 191 bool SlidingWindowPictureMarking(); 192 193 // Handle a gap in frame_num in the stream up to |frame_num|, by creating 194 // "non-existing" pictures (see spec). 195 bool HandleFrameNumGap(int frame_num); 196 197 // Start processing a new frame. 198 bool StartNewFrame(const H264SliceHeader* slice_hdr); 199 200 // All data for a frame received, process it and decode. 201 bool FinishPrevFrameIfPresent(); 202 203 // Called after we are done processing |pic|. Performs all operations to be 204 // done after decoding, including DPB management, reference picture marking 205 // and memory management operations. 206 // This will also output pictures if any have become ready to be outputted 207 // after processing |pic|. 208 bool FinishPicture(scoped_refptr<H264Picture> pic); 209 210 // Clear DPB contents and remove all surfaces in DPB from *in_use_ list. 211 // Cleared pictures will be made available for decode, unless they are 212 // at client waiting to be displayed. 213 void ClearDPB(); 214 215 // Commits all pending data for HW decoder and starts HW decoder. 216 bool DecodePicture(); 217 218 // Notifies client that a picture is ready for output. 219 void OutputPic(scoped_refptr<H264Picture> pic); 220 221 // Output all pictures in DPB that have not been outputted yet. 222 bool OutputAllRemainingPics(); 223 224 // Decoder state. 225 State state_; 226 227 // Parser in use. 228 H264Parser parser_; 229 230 // DPB in use. 231 H264DPB dpb_; 232 233 // Picture currently being processed/decoded. 234 scoped_refptr<H264Picture> curr_pic_; 235 236 // Reference picture lists, constructed for each frame. 237 H264Picture::Vector ref_pic_list_p0_; 238 H264Picture::Vector ref_pic_list_b0_; 239 H264Picture::Vector ref_pic_list_b1_; 240 241 // Global state values, needed in decoding. See spec. 242 int max_frame_num_; 243 int max_pic_num_; 244 int max_long_term_frame_idx_; 245 size_t max_num_reorder_frames_; 246 247 int prev_frame_num_; 248 int prev_ref_frame_num_; 249 int prev_frame_num_offset_; 250 bool prev_has_memmgmnt5_; 251 252 // Values related to previously decoded reference picture. 253 bool prev_ref_has_memmgmnt5_; 254 int prev_ref_top_field_order_cnt_; 255 int prev_ref_pic_order_cnt_msb_; 256 int prev_ref_pic_order_cnt_lsb_; 257 H264Picture::Field prev_ref_field_; 258 259 // Currently active SPS and PPS. 260 int curr_sps_id_; 261 int curr_pps_id_; 262 263 // Current NALU and slice header being processed. 264 std::unique_ptr<H264NALU> curr_nalu_; 265 std::unique_ptr<H264SliceHeader> curr_slice_hdr_; 266 267 // Output picture size. 268 Size pic_size_; 269 270 // PicOrderCount of the previously outputted frame. 271 int last_output_poc_; 272 273 H264Accelerator* accelerator_; 274 275 DISALLOW_COPY_AND_ASSIGN(H264Decoder); 276 }; 277 278 } // namespace media 279 280 #endif // H264_DECODER_H_ 281