static int ms_adpcm_decode_block(unsigned short *output, unsigned char *input,
int channels, int block_size)
{
int current_channel = 0;
int idelta[2];
int sample1[2];
int sample2[2];
int coeff1[2];
int coeff2[2];
int stream_ptr = 0;
int out_ptr = 0;
int upper_nibble = 1;
int nibble;
int snibble; // signed nibble
int predictor;
// fetch the header information, in stereo if both channels are present
if (input[stream_ptr] > 6)
mp_msg(MSGT_DECAUDIO, MSGL_WARN,
"MS ADPCM: coefficient (%d) out of range (should be [0..6])\n",
input[stream_ptr]);
coeff1[0] = ms_adapt_coeff1[input[stream_ptr]];
coeff2[0] = ms_adapt_coeff2[input[stream_ptr]];
stream_ptr++;
if (channels == 2)
{
if (input[stream_ptr] > 6)
mp_msg(MSGT_DECAUDIO, MSGL_WARN,
"MS ADPCM: coefficient (%d) out of range (should be [0..6])\n",
input[stream_ptr]);
coeff1[1] = ms_adapt_coeff1[input[stream_ptr]];
coeff2[1] = ms_adapt_coeff2[input[stream_ptr]];
stream_ptr++;
}
idelta[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(idelta[0]);
if (channels == 2)
{
idelta[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(idelta[1]);
}
sample1[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(sample1[0]);
if (channels == 2)
{
sample1[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(sample1[1]);
}
sample2[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(sample2[0]);
if (channels == 2)
{
sample2[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
SE_16BIT(sample2[1]);
}
if (channels == 1)
{
output[out_ptr++] = sample2[0];
output[out_ptr++] = sample1[0];
} else {
output[out_ptr++] = sample2[0];
output[out_ptr++] = sample2[1];
output[out_ptr++] = sample1[0];
output[out_ptr++] = sample1[1];
}
while (stream_ptr < block_size)
{
// get the next nibble
if (upper_nibble)
nibble = snibble = input[stream_ptr] >> 4;
else
nibble = snibble = input[stream_ptr++] & 0x0F;
upper_nibble ^= 1;
SE_4BIT(snibble);
predictor = (
((sample1[current_channel] * coeff1[current_channel]) +
(sample2[current_channel] * coeff2[current_channel])) / 256) +
(snibble * idelta[current_channel]);
CLAMP_S16(predictor);
sample2[current_channel] = sample1[current_channel];
sample1[current_channel] = predictor;
output[out_ptr++] = predictor;
// compute the next adaptive scale factor (a.k.a. the variable idelta)
idelta[current_channel] =
(ms_adapt_table[nibble] * idelta[current_channel]) / 256;
CLAMP_ABOVE_16(idelta[current_channel]);
// toggle the channel
current_channel ^= channels - 1;
}
static int ms_adpcm_decode_block(unsigned short *output, unsigned char *input,
int channels, int block_size)
{
int current_channel = 0;
int coeff_idx;
int idelta[2];
int sample1[2];
int sample2[2];
int coeff1[2];
int coeff2[2];
int stream_ptr = 0;
int out_ptr = 0;
int upper_nibble = 1;
int nibble;
int snibble; // signed nibble
int predictor;
if (channels != 1) channels = 2;
if (block_size < 7 * channels)
return -1;
// fetch the header information, in stereo if both channels are present
coeff_idx = check_coeff(input[stream_ptr]);
coeff1[0] = ms_adapt_coeff1[coeff_idx];
coeff2[0] = ms_adapt_coeff2[coeff_idx];
stream_ptr++;
if (channels == 2)
{
coeff_idx = check_coeff(input[stream_ptr]);
coeff1[1] = ms_adapt_coeff1[coeff_idx];
coeff2[1] = ms_adapt_coeff2[coeff_idx];
stream_ptr++;
}
idelta[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
if (channels == 2)
{
idelta[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
}
sample1[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
if (channels == 2)
{
sample1[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
}
sample2[0] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
if (channels == 2)
{
sample2[1] = LE_16(&input[stream_ptr]);
stream_ptr += 2;
}
if (channels == 1)
{
output[out_ptr++] = sample2[0];
output[out_ptr++] = sample1[0];
} else {
output[out_ptr++] = sample2[0];
output[out_ptr++] = sample2[1];
output[out_ptr++] = sample1[0];
output[out_ptr++] = sample1[1];
}
while (stream_ptr < block_size)
{
// get the next nibble
if (upper_nibble)
nibble = snibble = input[stream_ptr] >> 4;
else
nibble = snibble = input[stream_ptr++] & 0x0F;
upper_nibble ^= 1;
SE_4BIT(snibble);
// should this really be a division and not a shift?
// coefficients were originally scaled by for, which might have
// been an optimization for 8-bit CPUs _if_ a shift is correct
predictor = (
((sample1[current_channel] * coeff1[current_channel]) +
(sample2[current_channel] * coeff2[current_channel])) / 64) +
(snibble * idelta[current_channel]);
CLAMP_S16(predictor);
sample2[current_channel] = sample1[current_channel];
sample1[current_channel] = predictor;
output[out_ptr++] = predictor;
// compute the next adaptive scale factor (a.k.a. the variable idelta)
idelta[current_channel] =
(ms_adapt_table[nibble] * idelta[current_channel]) / 256;
CLAMP_ABOVE_16(idelta[current_channel]);
// toggle the channel
current_channel ^= channels - 1;
}