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Diffstat (limited to 'src/AACDecoder.cpp')
| -rw-r--r-- | src/AACDecoder.cpp | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/src/AACDecoder.cpp b/src/AACDecoder.cpp new file mode 100644 index 0000000..6cbe8c4 --- /dev/null +++ b/src/AACDecoder.cpp @@ -0,0 +1,160 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 2011 Martin Storsjo + * Copyright (C) 2017 Matthias P. Braendli + * Copyright (C) 2016 Stefan Pöschel + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. + * See the License for the specific language governing permissions + * and limitations under the License. + * ------------------------------------------------------------------- + */ + +#include "config.h" +#include "AACDecoder.h" +#include <stdexcept> + +AACDecoder::AACDecoder(const char* wavfilename) : + m_wav_writer(wavfilename) +{ + m_handle = aacDecoder_Open(TT_MP4_RAW, 1); + if (not m_handle) { + throw std::runtime_error("AACDecoder: error opening decoder"); + } +} + +void AACDecoder::decode_frame(uint8_t *data, size_t len) +{ + const bool dac_rate = data[2] & 0x40; + const bool sbr_flag = data[2] & 0x20; + const bool aac_channel_mode = data[2] & 0x10; + const bool ps_flag = data[2] & 0x08; + const uint8_t mpeg_surround_config = data[2] & 0x07; + + const int core_sr_index = dac_rate ? + (sbr_flag ? 6 : 3) : (sbr_flag ? 8 : 5); // 24/48/16/32 kHz + const int core_ch_config = aac_channel_mode ? 2 : 1; + const int extension_sr_index = dac_rate ? 3 : 5; // 48/32 kHz + + int au_start[6] = {}; + + int num_aus = dac_rate ? (sbr_flag ? 3 : 6) : (sbr_flag ? 2 : 4); + au_start[0] = dac_rate ? (sbr_flag ? 6 : 11) : (sbr_flag ? 5 : 8); + au_start[1] = data[3] << 4 | data[4] >> 4; + + if (num_aus >= 3) { + au_start[2] = (data[4] & 0x0F) << 8 | data[5]; + } + + if (num_aus >= 4) { + au_start[3] = data[6] << 4 | data[7] >> 4; + } + + if (num_aus == 6) { + au_start[4] = (data[7] & 0x0F) << 8 | data[8]; + au_start[5] = data[9] << 4 | data[10] >> 4; + } + + au_start[num_aus] = len; // end of the buffer + + for (int i = 0; i < num_aus; i++) { + if (au_start[i] >= au_start[i+1]) { + throw std::runtime_error(" AU ordering check failed\n"); + } + } + + if (not m_decoder_set_up) { + std::vector<uint8_t> asc; + + // AAC LC + asc.push_back(0b00010 << 3 | core_sr_index >> 1); + asc.push_back((core_sr_index & 0x01) << 7 | core_ch_config << 3 | 0b100); + + if (sbr_flag) { + // add SBR + asc.push_back(0x56); + asc.push_back(0xE5); + asc.push_back(0x80 | (extension_sr_index << 3)); + + if (ps_flag) { + // add PS + asc.back() |= 0x05; + asc.push_back(0x48); + asc.push_back(0x80); + } + } + + uint8_t* asc_array[1] {asc.data()}; + const unsigned int asc_sizeof_array[1] {(unsigned int) asc.size()}; + + AAC_DECODER_ERROR init_result = aacDecoder_ConfigRaw(m_handle, + asc_array, asc_sizeof_array); + if (init_result != AAC_DEC_OK) { + throw std::runtime_error( + "AACDecoderFDKAAC: error while aacDecoder_ConfigRaw: " + + std::to_string(init_result)); + } + + m_channels = aac_channel_mode || ps_flag ? 2 : 1; + size_t output_frame_len = 960 * 2 * m_channels * (sbr_flag ? 2 : 1); + m_output_frame.resize(output_frame_len); + fprintf(stderr, " Setting decoder output frame len %zu\n", output_frame_len); + + const int sample_rate = dac_rate ? 48000 : 32000; + m_wav_writer.initialise_header(sample_rate); + m_decoder_set_up = true; + + fprintf(stderr, " Set up decoder with %d Hz, %s%swith %d channels\n", + sample_rate, (sbr_flag ? "SBR " : ""), (ps_flag ? "PS " : ""), + m_channels); + + } + + const size_t AU_CRCLEN = 2; + for (int i = 0; i < num_aus; i++) { + uint8_t *au_data = data + au_start[i]; + size_t au_len = au_start[i+1] - au_start[i] - AU_CRCLEN; + decode_au(au_data, au_len); + } +} + +void AACDecoder::decode_au(uint8_t *data, size_t len) +{ + uint8_t* input_buffer[1] {data}; + const unsigned int input_buffer_size[1] {(unsigned int) len}; + unsigned int bytes_valid = len; + + // fill internal input buffer + AAC_DECODER_ERROR result = aacDecoder_Fill( + m_handle, input_buffer, input_buffer_size, &bytes_valid); + + if (result != AAC_DEC_OK) { + throw std::runtime_error( + "AACDecoderFDKAAC: error while aacDecoder_Fill: " + + std::to_string(result)); + } + + if (bytes_valid) { + throw std::runtime_error( + "AACDecoderFDKAAC: aacDecoder_Fill did not consume all bytes"); + } + + // decode audio + result = aacDecoder_DecodeFrame(m_handle, + (short int*)m_output_frame.data(), m_output_frame.size(), 0); + if (result != AAC_DEC_OK) { + throw std::runtime_error( + "AACDecoderFDKAAC: error while aacDecoder_DecodeFrame: " + + std::to_string(result)); + } + + m_wav_writer.write_data(m_output_frame.data(), m_output_frame.size()); +} |