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| /* | |
| Copyright 2015 Google Inc. All rights reserved. | |
| 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.*/ | |
| class FileResource; | |
| enum WaveCodingType { | |
| PCM16 = 0, | |
| PCM8, | |
| ULAW8, | |
| ISAC_18kbps, | |
| ISAC_20kbps, | |
| ISAC_22kbps, | |
| ISAC_24kbps, | |
| ISAC_26kbps, | |
| ISAC_30kbps | |
| }; | |
| class WavRiffCodec { | |
| public: | |
| WavRiffCodec() { } | |
| ~WavRiffCodec() { } | |
| // The header is expected to be in the format: | |
| // | |
| // offset size description value | |
| // 0x00 4 Chunk ID "RIFF" | |
| // 0x04 4 Chunk data size file size - 8 | |
| // 0x08 4 RIFF Type "WAVE" | |
| // 0x10 Wave chunks | |
| // | |
| // A boolean success indicator can be used to check that the header was read. | |
| bool ReadHeader(FileResource *fr, | |
| int32_t *num_samples_per_channel, | |
| int32_t *sample_rate); | |
| bool ReadAudioData(int32_t wave_start, | |
| int32_t num_samples, | |
| std::vector<int16_t> *samples, | |
| FileResource *fr); | |
| bool ReadAudioContainer(int container_size_in_bytes, | |
| std::vector<int16_t> *samples, | |
| FileResource *fr); | |
| bool Initialize(WaveCodingType coding_type); | |
| private: | |
| bool ReadChunk(FileResource *fr, std::string *chunk) const; | |
| bool CheckChunk(FileResource *fr, const char *data) const; | |
| WaveCodingType coding_type_; | |
| }; | |
| class UlawCodec { | |
| public: | |
| uint8_t Int16ToUlaw(int16_t pcm_val) const; | |
| int16_t UlawToInt16(uint8_t ulaw) const; | |
| private: | |
| int16_t SegmentSearch(int16_t val, const int16_t *table, int size) const; | |
| // Table and constants for mu-law coding and decoding | |
| static const int16_t seg_uend[8]; | |
| static const int16_t kBias; // Bias for linear code. | |
| static const int16_t kClip; // max. linear value | |
| static const int16_t kSignBit; // Sign bit for a A-law byte. | |
| static const int16_t kQuantMask; // Quantization field mask. | |
| static const int16_t kSegShift; // Left shift for segment number. | |
| static const int16_t kSegMask; // Segment field mask. | |
| }; | |