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#include "avi_ima_adpcm_decoder.h"
#include "../f263/BitReader.h"
#pragma pack(push, 1)
struct ima_adpcm_format
{
nsavi::audio_format format;
uint16_t samples_per_block;
};
#pragma pack(pop)
IMA_ADPCM_AVIDecoder::IMA_ADPCM_AVIDecoder(const ima_adpcm_format *adpcmformat, const nsavi::STRH *stream_header) : adpcmformat(adpcmformat), stream_header(stream_header)
{
}
int IMA_ADPCM_AVIDecoder::OutputFrameSize(size_t *frame_size)
{
int channels = adpcmformat->format.channels;
*frame_size = ((adpcmformat->format.block_align - 7*channels)*2 + 2*channels) * 2;
return AVI_SUCCESS;
}
int IMA_ADPCM_AVIDecoder::GetOutputProperties(unsigned int *sampleRate, unsigned int *channels, unsigned int *bitsPerSample, bool *isFloat)
{
if (adpcmformat)
{
*sampleRate = adpcmformat->format.sample_rate;
*channels = adpcmformat->format.channels;
*bitsPerSample = 16;
*isFloat = false;
return AVI_SUCCESS;
}
else
{
return AVI_FAILURE;
}
}
static int index_table[16] = {
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8
};
static 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 IMA_ADPCM_AVIDecoder::DecodeChunk(uint16_t type, void **inputBuffer, size_t *inputBufferBytes, void *outputBuffer, size_t *outputBufferBytes)
{
if (adpcmformat->format.channels == 1)
{
size_t adpcm_stream_length = *inputBufferBytes;
if (adpcm_stream_length < adpcmformat->format.block_align) // i'm not even going to consider the possibility of adpcm frames split across avi chunks
return AVI_FAILURE;
adpcm_stream_length = adpcmformat->format.block_align; // do one block at a time, in_avi will call us again
if (adpcm_stream_length < 7)
return AVI_FAILURE;
int16_t *out16 = (int16_t *)outputBuffer;
size_t out16_length = *outputBufferBytes/2;
const uint8_t *adpcm_data = (const uint8_t *)(*inputBuffer);
int predictor = *(int16_t *)adpcm_data;
*out16++ = predictor;
adpcm_data+=2;
out16_length--;
int step_index = *adpcm_data;
if (step_index > 88)
return AVI_FAILURE;
adpcm_data+=2;
BitReader reader;
reader.data = adpcm_data;
reader.numBits = (uint32_t)(*inputBufferBytes - 4)*8;
while (reader.numBits >= 8 && out16_length)
{
int diff, step, nibble;
step = step_table[step_index];
nibble = reader.getbits(4);
step_index += index_table[nibble];
step_index = min(step_index, 88);
step_index = max(step_index, 0);
diff = step>>3;
if(nibble&4)
diff += step;
if(nibble&2)
diff += step>>1;
if(nibble&1)
diff += step>>2;
if (nibble&8)
predictor -= diff;
else
predictor += diff;
predictor = min(predictor, 32767);
predictor = max(predictor, -32768);
*out16++ = predictor;
out16_length--;
}
*inputBuffer = (uint8_t *)(*inputBuffer) + adpcm_stream_length;
*inputBufferBytes -= adpcm_stream_length;
*outputBufferBytes = adpcmformat->samples_per_block*2;
return AVI_SUCCESS;
}
else if (adpcmformat->format.channels == 2)
{
size_t adpcm_stream_length = *inputBufferBytes;
if (adpcm_stream_length < adpcmformat->format.block_align) // i'm not even going to consider the possibility of adpcm frames split across avi chunks
return AVI_FAILURE;
adpcm_stream_length = adpcmformat->format.block_align; // do one block at a time, in_avi will call us again
if (adpcm_stream_length < 8)
return AVI_FAILURE;
int16_t *out16 = (int16_t *)outputBuffer;
size_t out16_length = *outputBufferBytes/2;
const uint8_t *adpcm_data = (const uint8_t *)(*inputBuffer);
int predictor_left = *(int16_t *)adpcm_data;
*out16++ = predictor_left;
adpcm_data+=2;
out16_length--;
int step_index_left = *adpcm_data;
if (step_index_left > 88)
return AVI_FAILURE;
adpcm_data+=2;
int predictor_right = *(int16_t *)adpcm_data;
*out16++ = predictor_right;
adpcm_data+=2;
out16_length--;
int step_index_right = *adpcm_data;
if (step_index_right > 88)
return AVI_FAILURE;
adpcm_data+=2;
BitReader reader;
reader.data = adpcm_data;
reader.numBits = (uint32_t)(*inputBufferBytes - 8)*8;
while (reader.numBits >= 8 && out16_length > 15)
{
int nibbles_left[8] = {0};
int nibbles_right[8] = {0};
for (int i=0;i<8;i++)
nibbles_left[i] = reader.getbits(4);
for (int i=0;i<8;i++)
nibbles_right[i] = reader.getbits(4);
for (int i=0;i<8;i++)
{
int diff, step, nibble;
step = step_table[step_index_left];
nibble = nibbles_left[i];
step_index_left += index_table[nibble];
step_index_left = min(step_index_left, 88);
step_index_left = max(step_index_left, 0);
diff = step>>3;
if(nibble&4)
diff += step;
if(nibble&2)
diff += step>>1;
if(nibble&1)
diff += step>>2;
if (nibble&8)
predictor_left -= diff;
else
predictor_left += diff;
predictor_left = min(predictor_left, 32767);
predictor_left = max(predictor_left, -32768);
*out16++ = predictor_left;
out16_length--;
step = step_table[step_index_right];
nibble =nibbles_right[i];
step_index_right += index_table[nibble];
step_index_right = min(step_index_right, 88);
step_index_right = max(step_index_right, 0);
diff = step>>3;
if(nibble&4)
diff += step;
if(nibble&2)
diff += step>>1;
if(nibble&1)
diff += step>>2;
if (nibble&8)
predictor_right -= diff;
else
predictor_right += diff;
predictor_right = min(predictor_right, 32767);
predictor_right = max(predictor_right, -32768);
*out16++ = predictor_right;
out16_length--;
}
}
*inputBuffer = (uint8_t *)(*inputBuffer) + adpcm_stream_length;
*inputBufferBytes -= adpcm_stream_length;
*outputBufferBytes = adpcmformat->samples_per_block*4;
return AVI_SUCCESS;
}
return AVI_FAILURE;
}
void IMA_ADPCM_AVIDecoder::Close()
{
delete this;
}
#define CBCLASS IMA_ADPCM_AVIDecoder
START_DISPATCH;
CB(OUTPUT_FRAME_SIZE, OutputFrameSize)
CB(GET_OUTPUT_PROPERTIES, GetOutputProperties)
CB(DECODE_CHUNK, DecodeChunk)
VCB(CLOSE, Close)
END_DISPATCH;
#undef CBCLASS
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