diff options
Diffstat (limited to 'Src/adpcm/flv_adpcm_decoder.cpp')
| -rw-r--r-- | Src/adpcm/flv_adpcm_decoder.cpp | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/Src/adpcm/flv_adpcm_decoder.cpp b/Src/adpcm/flv_adpcm_decoder.cpp new file mode 100644 index 00000000..69e02948 --- /dev/null +++ b/Src/adpcm/flv_adpcm_decoder.cpp @@ -0,0 +1,141 @@ +#include "flv_adpcm_decoder.h" +#include "../f263/BitReader.h" + +int FLVDecoderCreator::CreateAudioDecoder(int stereo, int bits, int sample_rate, int format_type, ifc_flvaudiodecoder **decoder) +{ + if (format_type == FLV::AUDIO_FORMAT_ADPCM) + { + *decoder = new FLVADPCM(stereo?2:1); + return CREATEDECODER_SUCCESS; + } + return CREATEDECODER_NOT_MINE; +} + +int FLVDecoderCreator::HandlesAudio(int format_type) +{ + if (format_type == FLV::AUDIO_FORMAT_ADPCM) + { + return CREATEDECODER_SUCCESS; + } + return CREATEDECODER_NOT_MINE; +} + +#define CBCLASS FLVDecoderCreator +START_DISPATCH; +CB(CREATE_AUDIO_DECODER, CreateAudioDecoder) +CB(HANDLES_AUDIO, HandlesAudio) +END_DISPATCH; +#undef CBCLASS + +/* --- */ +FLVADPCM::FLVADPCM(unsigned int channels) : channels(channels) +{ + +} + +int FLVADPCM::GetOutputFormat(unsigned int *sample_rate, unsigned int *channels, unsigned int *bits) +{ + *channels = this->channels; + *bits = 16; + return FLV_AUDIO_SUCCESS; +} + +// padded to zero where table size is less then 16 +static const int swf_index_tables[4][16] = { + /*2*/ { -1, 2 }, + /*3*/ { -1, -1, 2, 4 }, + /*4*/ { -1, -1, -1, -1, 2, 4, 6, 8 }, + /*5*/ { -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 } +}; + +static const int step_table[89] = { + 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, + 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, + 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, + 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, + 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, + 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, + 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, + 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, + 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 +}; + +int FLVADPCM::DecodeSample(const void *input_buffer, size_t input_buffer_bytes, void *_samples, size_t *samples_size_bytes, double *bitrate) +{ + int predictors[2] = {0, 0}; + int16_t step_indices[2] = {0, 0}; + + int16_t *samples = (int16_t *)_samples; + const size_t max_samples = *samples_size_bytes / sizeof(int16_t); + + BitReader bit_reader; + bit_reader.data = (uint8_t *)input_buffer; + bit_reader.numBits = (uint32_t)input_buffer_bytes * 8; + + uint32_t bits = bit_reader.getbits(2); + const int *table = swf_index_tables[bits]; + int k0 = 1 << bits++; + int signmask = 1 << bits++; + + size_t sample_num=0; + while (bit_reader.size() >= 22*channels) + { + for (size_t i = 0; i != channels; i++) + { + samples[sample_num++] = predictors[i] = ((int32_t)bit_reader.getbits(16) << 16) >> 16; + step_indices[i] = bit_reader.getbits(6); + } + + while (bit_reader.size() > bits*channels && sample_num < max_samples) + { + for (size_t i = 0; i != channels; i++) + { + int delta = bit_reader.getbits(bits); + int step = step_table[step_indices[i]]; + long vpdiff = 0; + int k = k0; + + do { + if (delta & k) + vpdiff += step; + step >>= 1; + k >>= 1; + } while(k); + vpdiff += step; + + if (delta & signmask) + predictors[i] -= vpdiff; + else + predictors[i] += vpdiff; + + step_indices[i] += table[delta & (~signmask)]; + + if (step_indices[i] < 0) step_indices[i] = 0; + if (step_indices[i] > 88) step_indices[i] = 88; + + if (predictors[i] > 32767) predictors[i] = 32767; + if (predictors[i] < -32768) predictors[i] = -32768; + + samples[sample_num++] = predictors[i]; + } + } + } + + *samples_size_bytes = sample_num * sizeof(int16_t); + + return FLV_AUDIO_SUCCESS; +} + + +void FLVADPCM::Close() +{ + delete this; +} + +#define CBCLASS FLVADPCM +START_DISPATCH; +CB(FLV_AUDIO_GETOUTPUTFORMAT, GetOutputFormat) +CB(FLV_AUDIO_DECODE, DecodeSample) +VCB(FLV_AUDIO_CLOSE, Close) +END_DISPATCH; +#undef CBCLASS
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