/* * Assorted DPCM codecs * Copyright (c) 2003 The ffmpeg Project. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ /** * @file: dpcm.c * Assorted DPCM (differential pulse code modulation) audio codecs * by Mike Melanson (melanson@pcisys.net) * for more information on the specific data formats, visit: * http://www.pcisys.net/~melanson/codecs/simpleaudio.html */ #include "avcodec.h" typedef struct DPCMContext { int channels; short roq_square_array[256]; int last_delta[2]; } DPCMContext; #define SATURATE_S16(x) if (x < -32768) x = -32768; \ else if (x > 32767) x = 32767; #define SE_16BIT(x) if (x & 0x8000) x -= 0x10000; #define LE_16(x) ((((uint8_t*)(x))[1] << 8) | ((uint8_t*)(x))[0]) #define LE_32(x) ((((uint8_t*)(x))[3] << 24) | \ (((uint8_t*)(x))[2] << 16) | \ (((uint8_t*)(x))[1] << 8) | \ ((uint8_t*)(x))[0]) static int interplay_delta_table[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 47, 51, 56, 61, 66, 72, 79, 86, 94, 102, 112, 122, 133, 145, 158, 173, 189, 206, 225, 245, 267, 292, 318, 348, 379, 414, 452, 493, 538, 587, 640, 699, 763, 832, 908, 991, 1081, 1180, 1288, 1405, 1534, 1673, 1826, 1993, 2175, 2373, 2590, 2826, 3084, 3365, 3672, 4008, 4373, 4772, 5208, 5683, 6202, 6767, 7385, 8059, 8794, 9597, 10472, 11428, 12471, 13609, 14851, 16206, 17685, 19298, 21060, 22981, 25078, 27367, 29864, 32589, -29973, -26728, -23186, -19322, -15105, -10503, -5481, -1, 1, 1, 5481, 10503, 15105, 19322, 23186, 26728, 29973, -32589, -29864, -27367, -25078, -22981, -21060, -19298, -17685, -16206, -14851, -13609, -12471, -11428, -10472, -9597, -8794, -8059, -7385, -6767, -6202, -5683, -5208, -4772, -4373, -4008, -3672, -3365, -3084, -2826, -2590, -2373, -2175, -1993, -1826, -1673, -1534, -1405, -1288, -1180, -1081, -991, -908, -832, -763, -699, -640, -587, -538, -493, -452, -414, -379, -348, -318, -292, -267, -245, -225, -206, -189, -173, -158, -145, -133, -122, -112, -102, -94, -86, -79, -72, -66, -61, -56, -51, -47, -43, -42, -41, -40, -39, -38, -37, -36, -35, -34, -33, -32, -31, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21, -20, -19, -18, -17, -16, -15, -14, -13, -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1 }; static int dpcm_decode_init(AVCodecContext *avctx) { DPCMContext *s = avctx->priv_data; int i; short square; s->channels = avctx->channels; switch(avctx->codec->id) { case CODEC_ID_ROQ_DPCM: /* initialize square table */ for (i = 0; i < 128; i++) { square = i * i; s->roq_square_array[i] = square; s->roq_square_array[i + 128] = -square; } break; default: break; } return 0; } static int dpcm_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size) { DPCMContext *s = avctx->priv_data; int in, out = 0; int i; int predictor[2]; int channel_number = 0; short *output_samples = data; int sequence_number; switch(avctx->codec->id) { case CODEC_ID_ROQ_DPCM: if (s->channels == 1) predictor[0] = LE_16(&buf[6]); else { predictor[0] = buf[7] << 8; predictor[1] = buf[6] << 8; } SE_16BIT(predictor[0]); SE_16BIT(predictor[1]); /* decode the samples */ for (in = 8, out = 0; in < buf_size; in++, out++) { predictor[channel_number] += s->roq_square_array[buf[in]]; SATURATE_S16(predictor[channel_number]); output_samples[out] = predictor[channel_number]; /* toggle channel */ channel_number ^= s->channels - 1; } break; case CODEC_ID_INTERPLAY_DPCM: in = 0; sequence_number = LE_16(&buf[in]); in += 6; /* skip over the stream mask and stream length */ if (sequence_number == 1) { predictor[0] = LE_16(&buf[in]); in += 2; SE_16BIT(predictor[0]) if (s->channels == 2) { predictor[1] = LE_16(&buf[in]); SE_16BIT(predictor[1]) in += 2; } } else { for (i = 0; i < s->channels; i++) predictor[i] = s->last_delta[i]; } while (in < buf_size) { predictor[channel_number] += interplay_delta_table[buf[in++]]; SATURATE_S16(predictor[channel_number]); output_samples[out++] = predictor[channel_number]; /* toggle channel */ channel_number ^= s->channels - 1; } /* save predictors for next round */ for (i = 0; i < s->channels; i++) s->last_delta[i] = predictor[i]; break; } *data_size = out * sizeof(short); return buf_size; } AVCodec roq_dpcm_decoder = { "roq_dpcm", CODEC_TYPE_AUDIO, CODEC_ID_ROQ_DPCM, sizeof(DPCMContext), dpcm_decode_init, NULL, NULL, dpcm_decode_frame, }; AVCodec interplay_dpcm_decoder = { "interplay_dpcm", CODEC_TYPE_AUDIO, CODEC_ID_INTERPLAY_DPCM, sizeof(DPCMContext), dpcm_decode_init, NULL, NULL, dpcm_decode_frame, };