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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <vector>
#include "base/containers/span.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "media/base/limits.h"
#include "media/base/subsample_entry.h"
#include "media/gpu/accelerated_video_decoder.h"
#include "media/gpu/h264_dpb.h"
#include "media/gpu/media_gpu_export.h"
#include "media/video/h264_parser.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
namespace media {
// Clients of this class are expected to pass H264 Annex-B byte stream
// and are expected to provide an implementation of H264Accelerator for
// offloading final steps of the decoding process.
// This class must be created, called and destroyed on a single thread, and
// does nothing internally on any other thread.
class MEDIA_GPU_EXPORT H264Decoder : public AcceleratedVideoDecoder {
class MEDIA_GPU_EXPORT H264Accelerator {
// Methods may return kTryAgain if they need additional data (provided
// independently) in order to proceed. Examples are things like not having
// an appropriate key to decode encrypted content, or needing to wait
// until hardware buffers are available. This is not considered an
// unrecoverable error, but rather a pause to allow an application to
// independently provide the required data. When H264Decoder::Decode()
// is called again, it will attempt to resume processing of the stream
// by calling the same method again.
enum class Status {
// Operation completed successfully.
// Operation failed.
// Operation failed because some external data is missing. Retry the same
// operation later, once the data has been provided.
// Operation is not supported. Used by SetStream() to indicate that the
// Accelerator can not handle this operation.
virtual ~H264Accelerator();
// Create a new H264Picture that the decoder client can use for decoding
// and pass back to this accelerator for decoding or reference.
// When the picture is no longer needed by decoder, it will just drop
// its reference to it, and it may do so at any time.
// Note that this may return nullptr if accelerator is not able to provide
// any new pictures at given time. The decoder is expected to handle
// this situation as normal and return from Decode() with kRanOutOfSurfaces.
virtual scoped_refptr<H264Picture> CreateH264Picture() = 0;
// Submit metadata for the current frame, providing the current |sps| and
// |pps| for it, |dpb| has to contain all the pictures in DPB for current
// frame, and |ref_pic_p0/b0/b1| as specified in the H264 spec. Note that
// depending on the frame type, either p0, or b0 and b1 are used. |pic|
// contains information about the picture for the current frame.
// Note that this does not run decode in the accelerator and the decoder
// is expected to follow this call with one or more SubmitSlice() calls
// before calling SubmitDecode().
// Returns kOk if successful, kFail if there are errors, or kTryAgain if
// the accelerator needs additional data before being able to proceed.
virtual Status SubmitFrameMetadata(
const H264SPS* sps,
const H264PPS* pps,
const H264DPB& dpb,
const H264Picture::Vector& ref_pic_listp0,
const H264Picture::Vector& ref_pic_listb0,
const H264Picture::Vector& ref_pic_listb1,
scoped_refptr<H264Picture> pic) = 0;
// Used for handling CENCv1 streams where the entire slice header, except
// for the NALU type byte, is encrypted. |data| represents the encrypted
// ranges which will include any SEI NALUs along with the encrypted slice
// NALU. |subsamples| specifies what is encrypted and should have just a
// single clear byte for each and the rest is encrypted. |sps_nalu_data|
// and |pps_nalu_data| are the SPS and PPS NALUs respectively.
// |slice_header_out| should have its fields filled in upon successful
// return. Returns kOk if successful, kFail if there are errors, or
// kTryAgain if the accelerator needs additional data before being able to
// proceed.
virtual Status ParseEncryptedSliceHeader(
const std::vector<base::span<const uint8_t>>& data,
const std::vector<SubsampleEntry>& subsamples,
const std::vector<uint8_t>& sps_nalu_data,
const std::vector<uint8_t>& pps_nalu_data,
H264SliceHeader* slice_header_out);
// Submit one slice for the current frame, passing the current |pps| and
// |pic| (same as in SubmitFrameMetadata()), the parsed header for the
// current slice in |slice_hdr|, and the reordered |ref_pic_listX|,
// as per H264 spec.
// |data| pointing to the full slice (including the unparsed header) of
// |size| in bytes.
// |subsamples| specifies which part of the slice data is encrypted.
// This must be called one or more times per frame, before SubmitDecode().
// Note that |data| does not have to remain valid after this call returns.
// Returns kOk if successful, kFail if there are errors, or kTryAgain if
// the accelerator needs additional data before being able to proceed.
virtual Status SubmitSlice(
const H264PPS* pps,
const H264SliceHeader* slice_hdr,
const H264Picture::Vector& ref_pic_list0,
const H264Picture::Vector& ref_pic_list1,
scoped_refptr<H264Picture> pic,
const uint8_t* data,
size_t size,
const std::vector<SubsampleEntry>& subsamples) = 0;
// Execute the decode in hardware for |pic|, using all the slices and
// metadata submitted via SubmitFrameMetadata() and SubmitSlice() since
// the previous call to SubmitDecode().
// Returns kOk if successful, kFail if there are errors, or kTryAgain if
// the accelerator needs additional data before being able to proceed.
virtual Status SubmitDecode(scoped_refptr<H264Picture> pic) = 0;
// Schedule output (display) of |pic|. Note that returning from this
// method does not mean that |pic| has already been outputted (displayed),
// but guarantees that all pictures will be outputted in the same order
// as this method was called for them. Decoder may drop its reference
// to |pic| after calling this method.
// Return true if successful.
virtual bool OutputPicture(scoped_refptr<H264Picture> pic) = 0;
// Reset any current state that may be cached in the accelerator, dropping
// any cached parameters/slices that have not been committed yet.
virtual void Reset() = 0;
// Notifies the accelerator whenever there is a new stream to process.
// |stream| is the data in annex B format, which may include SPS and PPS
// NALUs when there is a configuration change. The first frame must contain
// the SPS and PPS NALUs. SPS and PPS NALUs may not be encrypted.
// |decrypt_config| is the config for decrypting the stream. The accelerator
// should use |decrypt_config| to keep track of the parts of |stream| that
// are encrypted. If kTryAgain is returned, the decoder will retry this call
// later. This method has a default implementation that returns
// kNotSupported.
virtual Status SetStream(base::span<const uint8_t> stream,
const DecryptConfig* decrypt_config);
H264Decoder(std::unique_ptr<H264Accelerator> accelerator,
VideoCodecProfile profile,
const VideoColorSpace& container_color_space = VideoColorSpace());
~H264Decoder() override;
// AcceleratedVideoDecoder implementation.
void SetStream(int32_t id, const DecoderBuffer& decoder) override;
bool Flush() override WARN_UNUSED_RESULT;
void Reset() override;
DecodeResult Decode() override WARN_UNUSED_RESULT;
gfx::Size GetPicSize() const override;
gfx::Rect GetVisibleRect() const override;
VideoCodecProfile GetProfile() const override;
uint8_t GetBitDepth() const override;
size_t GetRequiredNumOfPictures() const override;
size_t GetNumReferenceFrames() const override;
// Return true if we need to start a new picture.
static bool IsNewPrimaryCodedPicture(const H264Picture* curr_pic,
int curr_pps_id,
const H264SPS* sps,
const H264SliceHeader& slice_hdr);
// Fill a H264Picture in |pic| from given |sps| and |slice_hdr|. Return false
// when there is an error.
static bool FillH264PictureFromSliceHeader(const H264SPS* sps,
const H264SliceHeader& slice_hdr,
H264Picture* pic);
// Internal state of the decoder.
enum State {
// After initialization, need an SPS.
// Ready to decode from any point.
// After Reset(), need a resume point.
// The following keep track of what step is next in Decode() processing
// in order to resume properly after H264Decoder::kTryAgain (or another
// retryable error) is returned. The next time Decode() is called the call
// that previously failed will be retried and execution continues from
// there (if possible).
// Error in decode, can't continue.
// Process H264 stream structures.
bool ProcessSPS(int sps_id, bool* need_new_buffers);
// Processes a CENCv1 encrypted slice header and fills in |curr_slice_hdr_|
// with the relevant parsed fields.
H264Accelerator::Status ProcessEncryptedSliceHeader(
const std::vector<SubsampleEntry>& subsamples);
// Process current slice header to discover if we need to start a new picture,
// finishing up the current one.
H264Accelerator::Status PreprocessCurrentSlice();
// Process current slice as a slice of the current picture.
H264Accelerator::Status ProcessCurrentSlice();
// Initialize the current picture according to data in |slice_hdr|.
bool InitCurrPicture(const H264SliceHeader* slice_hdr);
// Initialize |pic| as a "non-existing" picture (see spec) with |frame_num|,
// to be used for frame gap concealment.
bool InitNonexistingPicture(scoped_refptr<H264Picture> pic, int frame_num);
// Calculate picture order counts for |pic| on initialization
// of a new frame (see spec).
bool CalculatePicOrderCounts(scoped_refptr<H264Picture> pic);
// Update PicNum values in pictures stored in DPB on creation of
// a picture with |frame_num|.
void UpdatePicNums(int frame_num);
bool UpdateMaxNumReorderFrames(const H264SPS* sps);
// Prepare reference picture lists for the current frame.
void PrepareRefPicLists();
// Prepare reference picture lists for the given slice.
bool ModifyReferencePicLists(const H264SliceHeader* slice_hdr,
H264Picture::Vector* ref_pic_list0,
H264Picture::Vector* ref_pic_list1);
// Construct initial reference picture lists for use in decoding of
// P and B pictures (see 8.2.4 in spec).
void ConstructReferencePicListsP();
void ConstructReferencePicListsB();
// Helper functions for reference list construction, per spec.
int PicNumF(const H264Picture& pic);
int LongTermPicNumF(const H264Picture& pic);
// Perform the reference picture lists' modification (reordering), as
// specified in spec (8.2.4).
// |list| indicates list number and should be either 0 or 1.
bool ModifyReferencePicList(const H264SliceHeader* slice_hdr,
int list,
H264Picture::Vector* ref_pic_listx);
// Perform reference picture memory management operations (marking/unmarking
// of reference pictures, long term picture management, discarding, etc.).
// See 8.2.5 in spec.
bool HandleMemoryManagementOps(scoped_refptr<H264Picture> pic);
bool ReferencePictureMarking(scoped_refptr<H264Picture> pic);
bool SlidingWindowPictureMarking();
// Handle a gap in frame_num in the stream up to |frame_num|, by creating
// "non-existing" pictures (see spec).
bool HandleFrameNumGap(int frame_num);
// Start processing a new frame.
H264Accelerator::Status StartNewFrame(const H264SliceHeader* slice_hdr);
// All data for a frame received, process it and decode.
H264Accelerator::Status FinishPrevFrameIfPresent();
// Called after we are done processing |pic|. Performs all operations to be
// done after decoding, including DPB management, reference picture marking
// and memory management operations.
// This will also output pictures if any have become ready to be outputted
// after processing |pic|.
bool FinishPicture(scoped_refptr<H264Picture> pic);
// Clear DPB contents and remove all surfaces in DPB from *in_use_ list.
// Cleared pictures will be made available for decode, unless they are
// at client waiting to be displayed.
void ClearDPB();
// Commits all pending data for HW decoder and starts HW decoder.
H264Accelerator::Status DecodePicture();
// Notifies client that a picture is ready for output.
bool OutputPic(scoped_refptr<H264Picture> pic);
// Output all pictures in DPB that have not been outputted yet.
bool OutputAllRemainingPics();
// Decoder state.
State state_;
// The colorspace for the h264 container.
const VideoColorSpace container_color_space_;
// Parser in use.
H264Parser parser_;
// Most recent call to SetStream().
const uint8_t* current_stream_ = nullptr;
size_t current_stream_size_ = 0;
// Decrypting config for the most recent data passed to SetStream().
std::unique_ptr<DecryptConfig> current_decrypt_config_;
// Keep track of when SetStream() is called so that
// H264Accelerator::SetStream() can be called.
bool current_stream_has_been_changed_ = false;
// DPB in use.
H264DPB dpb_;
// Current stream buffer id; to be assigned to pictures decoded from it.
int32_t stream_id_ = -1;
// Picture currently being processed/decoded.
scoped_refptr<H264Picture> curr_pic_;
// Reference picture lists, constructed for each frame.
H264Picture::Vector ref_pic_list_p0_;
H264Picture::Vector ref_pic_list_b0_;
H264Picture::Vector ref_pic_list_b1_;
// Global state values, needed in decoding. See spec.
int max_frame_num_;
int max_pic_num_;
int max_long_term_frame_idx_;
size_t max_num_reorder_frames_;
int prev_frame_num_;
int prev_ref_frame_num_;
int prev_frame_num_offset_;
bool prev_has_memmgmnt5_;
// Values related to previously decoded reference picture.
bool prev_ref_has_memmgmnt5_;
int prev_ref_top_field_order_cnt_;
int prev_ref_pic_order_cnt_msb_;
int prev_ref_pic_order_cnt_lsb_;
H264Picture::Field prev_ref_field_;
// Currently active SPS and PPS.
int curr_sps_id_;
int curr_pps_id_;
// Last PPS that was parsed. Used for full sample encryption, which has the
// assumption this is streaming content which does not switch between
// different PPSes in the stream (they are present once in the container for
// the stream).
int last_parsed_pps_id_;
// Copies of the last SPS and PPS NALUs, used for full sample encryption.
std::vector<uint8_t> last_sps_nalu_;
std::vector<uint8_t> last_pps_nalu_;
// Current NALU and slice header being processed.
std::unique_ptr<H264NALU> curr_nalu_;
std::unique_ptr<H264SliceHeader> curr_slice_hdr_;
// Encrypted SEI NALUs preceding a fully encrypted slice NALU. We need to
// save these that are part of a single sample so they can all be decrypted
// together.
std::vector<base::span<const uint8_t>> encrypted_sei_nalus_;
std::vector<SubsampleEntry> sei_subsamples_;
// These are absl::nullopt unless get recovery point SEI message after Reset.
// A frame_num of the frame at output order that is correct in content.
absl::optional<int> recovery_frame_num_;
// A value in the recovery point SEI message to compute |recovery_frame_num_|
// later.
absl::optional<int> recovery_frame_cnt_;
// Output picture size.
gfx::Size pic_size_;
// Output visible cropping rect.
gfx::Rect visible_rect_;
// Profile of input bitstream.
VideoCodecProfile profile_;
// Bit depth of input bitstream.
uint8_t bit_depth_ = 0;
// PicOrderCount of the previously outputted frame.
int last_output_poc_;
const std::unique_ptr<H264Accelerator> accelerator_;
} // namespace media
#endif // MEDIA_GPU_H264_DECODER_H_