| /* |
| * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| * |
| */ |
| |
| #include "common_video/h264/sps_vui_rewriter.h" |
| |
| #include <string.h> |
| #include <cstdint> |
| #include <vector> |
| |
| #include "common_video/h264/h264_common.h" |
| #include "common_video/h264/sps_parser.h" |
| #include "rtc_base/bit_buffer.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| #include "rtc_base/numerics/safe_minmax.h" |
| |
| namespace webrtc { |
| |
| // The maximum expected growth from adding a VUI to the SPS. It's actually |
| // closer to 24 or so, but better safe than sorry. |
| const size_t kMaxVuiSpsIncrease = 64; |
| |
| #define RETURN_FALSE_ON_FAIL(x) \ |
| if (!(x)) { \ |
| RTC_LOG_F(LS_ERROR) << " (line:" << __LINE__ << ") FAILED: " #x; \ |
| return false; \ |
| } |
| |
| #define COPY_UINT8(src, dest, tmp) \ |
| do { \ |
| RETURN_FALSE_ON_FAIL((src)->ReadUInt8(&tmp)); \ |
| if (dest) \ |
| RETURN_FALSE_ON_FAIL((dest)->WriteUInt8(tmp)); \ |
| } while (0) |
| |
| #define COPY_EXP_GOLOMB(src, dest, tmp) \ |
| do { \ |
| RETURN_FALSE_ON_FAIL((src)->ReadExponentialGolomb(&tmp)); \ |
| if (dest) \ |
| RETURN_FALSE_ON_FAIL((dest)->WriteExponentialGolomb(tmp)); \ |
| } while (0) |
| |
| #define COPY_BITS(src, dest, tmp, bits) \ |
| do { \ |
| RETURN_FALSE_ON_FAIL((src)->ReadBits(&tmp, bits)); \ |
| if (dest) \ |
| RETURN_FALSE_ON_FAIL((dest)->WriteBits(tmp, bits)); \ |
| } while (0) |
| |
| typedef const SpsParser::SpsState& Sps; |
| |
| bool CopyAndRewriteVui(Sps sps, |
| rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination, |
| SpsVuiRewriter::ParseResult* out_vui_rewritten); |
| bool CopyHrdParameters(rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination); |
| bool AddBitstreamRestriction(rtc::BitBufferWriter* destination, |
| uint32_t max_num_ref_frames); |
| bool CopyRemainingBits(rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination); |
| |
| SpsVuiRewriter::ParseResult SpsVuiRewriter::ParseAndRewriteSps( |
| const uint8_t* buffer, |
| size_t length, |
| absl::optional<SpsParser::SpsState>* sps, |
| rtc::Buffer* destination) { |
| // Create temporary RBSP decoded buffer of the payload (exlcuding the |
| // leading nalu type header byte (the SpsParser uses only the payload). |
| std::vector<uint8_t> rbsp_buffer = H264::ParseRbsp(buffer, length); |
| rtc::BitBuffer source_buffer(rbsp_buffer.data(), rbsp_buffer.size()); |
| absl::optional<SpsParser::SpsState> sps_state = |
| SpsParser::ParseSpsUpToVui(&source_buffer); |
| if (!sps_state) |
| return ParseResult::kFailure; |
| |
| *sps = sps_state; |
| |
| // We're going to completely muck up alignment, so we need a BitBuffer to |
| // write with. |
| rtc::Buffer out_buffer(length + kMaxVuiSpsIncrease); |
| rtc::BitBufferWriter sps_writer(out_buffer.data(), out_buffer.size()); |
| |
| // Check how far the SpsParser has read, and copy that data in bulk. |
| size_t byte_offset; |
| size_t bit_offset; |
| source_buffer.GetCurrentOffset(&byte_offset, &bit_offset); |
| memcpy(out_buffer.data(), rbsp_buffer.data(), |
| byte_offset + (bit_offset > 0 ? 1 : 0)); // OK to copy the last bits. |
| |
| // SpsParser will have read the vui_params_present flag, which we want to |
| // modify, so back off a bit; |
| if (bit_offset == 0) { |
| --byte_offset; |
| bit_offset = 7; |
| } else { |
| --bit_offset; |
| } |
| sps_writer.Seek(byte_offset, bit_offset); |
| |
| ParseResult vui_updated; |
| if (!CopyAndRewriteVui(*sps_state, &source_buffer, &sps_writer, |
| &vui_updated)) { |
| RTC_LOG(LS_ERROR) << "Failed to parse/copy SPS VUI."; |
| return ParseResult::kFailure; |
| } |
| |
| if (vui_updated == ParseResult::kVuiOk) { |
| // No update necessary after all, just return. |
| return vui_updated; |
| } |
| |
| if (!CopyRemainingBits(&source_buffer, &sps_writer)) { |
| RTC_LOG(LS_ERROR) << "Failed to parse/copy SPS VUI."; |
| return ParseResult::kFailure; |
| } |
| |
| // Pad up to next byte with zero bits. |
| sps_writer.GetCurrentOffset(&byte_offset, &bit_offset); |
| if (bit_offset > 0) { |
| sps_writer.WriteBits(0, 8 - bit_offset); |
| ++byte_offset; |
| bit_offset = 0; |
| } |
| |
| RTC_DCHECK(byte_offset <= length + kMaxVuiSpsIncrease); |
| RTC_CHECK(destination != nullptr); |
| |
| out_buffer.SetSize(byte_offset); |
| |
| // Write updates SPS to destination with added RBSP |
| H264::WriteRbsp(out_buffer.data(), out_buffer.size(), destination); |
| |
| return ParseResult::kVuiRewritten; |
| } |
| |
| bool CopyAndRewriteVui(Sps sps, |
| rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination, |
| SpsVuiRewriter::ParseResult* out_vui_rewritten) { |
| uint32_t golomb_tmp; |
| uint32_t bits_tmp; |
| |
| // |
| // vui_parameters_present_flag: u(1) |
| // |
| RETURN_FALSE_ON_FAIL(destination->WriteBits(1, 1)); |
| |
| // ********* IMPORTANT! ********** |
| // Now we're at the VUI, so we want to (1) add it if it isn't present, and |
| // (2) rewrite frame reordering values so no reordering is allowed. |
| if (!sps.vui_params_present) { |
| // Write a simple VUI with the parameters we want and 0 for all other flags. |
| // There are 8 flags to be off before the bitstream restriction flag. |
| RETURN_FALSE_ON_FAIL(destination->WriteBits(0, 8)); |
| // bitstream_restriction_flag: u(1) |
| RETURN_FALSE_ON_FAIL(destination->WriteBits(1, 1)); |
| RETURN_FALSE_ON_FAIL( |
| AddBitstreamRestriction(destination, sps.max_num_ref_frames)); |
| } else { |
| // Parse out the full VUI. |
| // aspect_ratio_info_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // aspect_ratio_idc: u(8) |
| COPY_BITS(source, destination, bits_tmp, 8); |
| if (bits_tmp == 255u) { // Extended_SAR |
| // sar_width/sar_height: u(16) each. |
| COPY_BITS(source, destination, bits_tmp, 32); |
| } |
| } |
| // overscan_info_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // overscan_appropriate_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| } |
| // video_signal_type_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // video_format + video_full_range_flag: u(3) + u(1) |
| COPY_BITS(source, destination, bits_tmp, 4); |
| // colour_description_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // colour_primaries, transfer_characteristics, matrix_coefficients: |
| // u(8) each. |
| COPY_BITS(source, destination, bits_tmp, 24); |
| } |
| } |
| // chroma_loc_info_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // chroma_sample_loc_type_(top|bottom)_field: ue(v) each. |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| } |
| // timing_info_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| if (bits_tmp == 1) { |
| // num_units_in_tick, time_scale: u(32) each |
| COPY_BITS(source, destination, bits_tmp, 32); |
| COPY_BITS(source, destination, bits_tmp, 32); |
| // fixed_frame_rate_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| } |
| // nal_hrd_parameters_present_flag: u(1) |
| uint32_t nal_hrd_parameters_present_flag; |
| COPY_BITS(source, destination, nal_hrd_parameters_present_flag, 1); |
| if (nal_hrd_parameters_present_flag == 1) { |
| RETURN_FALSE_ON_FAIL(CopyHrdParameters(source, destination)); |
| } |
| // vcl_hrd_parameters_present_flag: u(1) |
| uint32_t vcl_hrd_parameters_present_flag; |
| COPY_BITS(source, destination, vcl_hrd_parameters_present_flag, 1); |
| if (vcl_hrd_parameters_present_flag == 1) { |
| RETURN_FALSE_ON_FAIL(CopyHrdParameters(source, destination)); |
| } |
| if (nal_hrd_parameters_present_flag == 1 || |
| vcl_hrd_parameters_present_flag == 1) { |
| // low_delay_hrd_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| } |
| // pic_struct_present_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| |
| // bitstream_restriction_flag: u(1) |
| uint32_t bitstream_restriction_flag; |
| RETURN_FALSE_ON_FAIL(source->ReadBits(&bitstream_restriction_flag, 1)); |
| RETURN_FALSE_ON_FAIL(destination->WriteBits(1, 1)); |
| if (bitstream_restriction_flag == 0) { |
| // We're adding one from scratch. |
| RETURN_FALSE_ON_FAIL( |
| AddBitstreamRestriction(destination, sps.max_num_ref_frames)); |
| } else { |
| // We're replacing. |
| // motion_vectors_over_pic_boundaries_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| // max_bytes_per_pic_denom: ue(v) |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| // max_bits_per_mb_denom: ue(v) |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| // log2_max_mv_length_horizontal: ue(v) |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| // log2_max_mv_length_vertical: ue(v) |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| // ********* IMPORTANT! ********** |
| // The next two are the ones we need to set to low numbers: |
| // max_num_reorder_frames: ue(v) |
| // max_dec_frame_buffering: ue(v) |
| // However, if they are already set to no greater than the numbers we |
| // want, then we don't need to be rewriting. |
| uint32_t max_num_reorder_frames, max_dec_frame_buffering; |
| RETURN_FALSE_ON_FAIL( |
| source->ReadExponentialGolomb(&max_num_reorder_frames)); |
| RETURN_FALSE_ON_FAIL( |
| source->ReadExponentialGolomb(&max_dec_frame_buffering)); |
| if (max_num_reorder_frames == 0 && |
| max_dec_frame_buffering <= sps.max_num_ref_frames) { |
| RTC_LOG(LS_INFO) << "VUI bitstream already contains an optimal VUI."; |
| *out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiOk; |
| return true; |
| } |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(0)); |
| RETURN_FALSE_ON_FAIL( |
| destination->WriteExponentialGolomb(sps.max_num_ref_frames)); |
| } |
| } |
| *out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiRewritten; |
| return true; |
| } |
| |
| // Copies a VUI HRD parameters segment. |
| bool CopyHrdParameters(rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination) { |
| uint32_t golomb_tmp; |
| uint32_t bits_tmp; |
| |
| // cbp_cnt_minus1: ue(v) |
| uint32_t cbp_cnt_minus1; |
| COPY_EXP_GOLOMB(source, destination, cbp_cnt_minus1); |
| // bit_rate_scale and cbp_size_scale: u(4) each |
| COPY_BITS(source, destination, bits_tmp, 8); |
| for (size_t i = 0; i <= cbp_cnt_minus1; ++i) { |
| // bit_rate_value_minus1 and cbp_size_value_minus1: ue(v) each |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| COPY_EXP_GOLOMB(source, destination, golomb_tmp); |
| // cbr_flag: u(1) |
| COPY_BITS(source, destination, bits_tmp, 1); |
| } |
| // initial_cbp_removal_delay_length_minus1: u(5) |
| COPY_BITS(source, destination, bits_tmp, 5); |
| // cbp_removal_delay_length_minus1: u(5) |
| COPY_BITS(source, destination, bits_tmp, 5); |
| // dbp_output_delay_length_minus1: u(5) |
| COPY_BITS(source, destination, bits_tmp, 5); |
| // time_offset_length: u(5) |
| COPY_BITS(source, destination, bits_tmp, 5); |
| return true; |
| } |
| |
| // These functions are similar to webrtc::H264SpsParser::Parse, and based on the |
| // same version of the H.264 standard. You can find it here: |
| // http://www.itu.int/rec/T-REC-H.264 |
| |
| // Adds a bitstream restriction VUI segment. |
| bool AddBitstreamRestriction(rtc::BitBufferWriter* destination, |
| uint32_t max_num_ref_frames) { |
| // motion_vectors_over_pic_boundaries_flag: u(1) |
| // Default is 1 when not present. |
| RETURN_FALSE_ON_FAIL(destination->WriteBits(1, 1)); |
| // max_bytes_per_pic_denom: ue(v) |
| // Default is 2 when not present. |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(2)); |
| // max_bits_per_mb_denom: ue(v) |
| // Default is 1 when not present. |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(1)); |
| // log2_max_mv_length_horizontal: ue(v) |
| // log2_max_mv_length_vertical: ue(v) |
| // Both default to 16 when not present. |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(16)); |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(16)); |
| |
| // ********* IMPORTANT! ********** |
| // max_num_reorder_frames: ue(v) |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(0)); |
| // max_dec_frame_buffering: ue(v) |
| RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(max_num_ref_frames)); |
| return true; |
| } |
| |
| bool CopyRemainingBits(rtc::BitBuffer* source, |
| rtc::BitBufferWriter* destination) { |
| uint32_t bits_tmp; |
| // Try to get at least the destination aligned. |
| if (source->RemainingBitCount() > 0 && source->RemainingBitCount() % 8 != 0) { |
| size_t misaligned_bits = source->RemainingBitCount() % 8; |
| COPY_BITS(source, destination, bits_tmp, misaligned_bits); |
| } |
| while (source->RemainingBitCount() > 0) { |
| auto count = rtc::SafeMin<size_t>(32u, source->RemainingBitCount()); |
| COPY_BITS(source, destination, bits_tmp, count); |
| } |
| // TODO(noahric): The last byte could be all zeroes now, which we should just |
| // strip. |
| return true; |
| } |
| |
| } // namespace webrtc |
