diff options
Diffstat (limited to 'adpcm.c')
-rw-r--r-- | adpcm.c | 140 |
1 files changed, 140 insertions, 0 deletions
@@ -1,6 +1,11 @@ /* Unified ADPCM Decoder for MPlayer + This file is in charge of decoding all of the various ADPCM data + formats that various entities have created. Details about the data + formats can be found here: + http://www.pcisys.net/~melanson/codecs/ + (C) 2001 Mike Melanson */ @@ -13,13 +18,60 @@ #define LE_16(x) (le2me_16(*(unsigned short *)(x))) #define LE_32(x) (le2me_32(*(unsigned int *)(x))) +// pertinent tables +static int adpcm_step[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 +}; + +static int adpcm_index[16] = +{ + -1, -1, -1, -1, 2, 4, 6, 8, + -1, -1, -1, -1, 2, 4, 6, 8 +}; + +static int format_0x62_table[16] = +{ + 1, 3, 5, 7, 9, 11, 13, 15, + -1, -3, -5, -7, -9, -11, -13, -15 +}; + +static int ms_adapt_table[] = +{ + 230, 230, 230, 230, 307, 409, 512, 614, + 768, 614, 512, 409, 307, 230, 230, 230 +}; + +static int ms_adapt_coeff1[] = +{ + 256, 512, 0, 192, 240, 460, 392 +}; + +static int ms_adapt_coeff2[] = +{ + 0, -256, 0, 64, 0, -208, -232 +}; + +// useful macros // clamp a number between 0 and 88 #define CLAMP_0_TO_88(x) if (x < 0) x = 0; else if (x > 88) x = 88; // clamp a number within a signed 16-bit range #define CLAMP_S16(x) if (x < -32768) x = -32768; \ else if (x > 32767) x = 32767; +// clamp a number above 16 +#define CLAMP_ABOVE_16(x) if (x < 16) x = 16; // sign extend a 16-bit value #define SE_16BIT(x) if (x & 0x8000) x -= 0x10000; +// sign extend a 4-bit value +#define SE_4BIT(x) if (x & 0x8) x -= 0x10; void ima_dvi_decode_nibbles(unsigned short *output, int channels, int predictor_l, int index_l, @@ -129,3 +181,91 @@ int ima_adpcm_decode_block(unsigned short *output, unsigned char *input, return IMA_ADPCM_SAMPLES_PER_BLOCK * channels; } + +int ms_adpcm_decode_block(unsigned short *output, unsigned char *input, + int channels) +{ + 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 + coeff1[0] = ms_adapt_coeff1[input[stream_ptr]]; + coeff2[0] = ms_adapt_coeff2[input[stream_ptr]]; + stream_ptr++; + if (channels == 2) + { + 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]); + } + + while (stream_ptr < MS_ADPCM_BLOCK_SIZE * channels) + { + // 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; + } + + return MS_ADPCM_SAMPLES_PER_BLOCK * channels; +} |