/* * 8SVX audio decoder * Copyright (C) 2008 Jaikrishnan Menon * * This file is part of FFmpeg. * * FFmpeg 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 2.1 of the License, or (at your option) any later version. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file 8svx.c * 8svx audio decoder * @author Jaikrishnan Menon * supports: fibonacci delta encoding * : exponential encoding */ #include "avcodec.h" /** decoder context */ typedef struct EightSvxContext { int16_t fib_acc; int16_t *table; } EightSvxContext; const static int16_t fibonacci[16] = { -34<<8, -21<<8, -13<<8, -8<<8, -5<<8, -3<<8, -2<<8, -1<<8, 0, 1<<8, 2<<8, 3<<8, 5<<8, 8<<8, 13<<8, 21<<8 }; const static int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8, -8<<8, -4<<8, -2<<8, -1<<8, 0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8, 32<<8, 64<<8 }; /** decode a frame */ static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size, const uint8_t *buf, int buf_size) { EightSvxContext *esc = avctx->priv_data; int16_t *out_data = data; int consumed = buf_size; const uint8_t *buf_end = buf + buf_size; if((*data_size >> 2) < buf_size) return -1; if(avctx->frame_number == 0) { esc->fib_acc = buf[1] << 8; buf_size -= 2; buf += 2; } *data_size = buf_size << 2; while(buf < buf_end) { uint8_t d = *buf++; esc->fib_acc += esc->table[d & 0x0f]; *out_data++ = esc->fib_acc; esc->fib_acc += esc->table[d >> 4]; *out_data++ = esc->fib_acc; } return consumed; } /** initialize 8svx decoder */ static av_cold int eightsvx_decode_init(AVCodecContext *avctx) { EightSvxContext *esc = avctx->priv_data; switch(avctx->codec->id) { case CODEC_ID_8SVX_FIB: esc->table = fibonacci; break; case CODEC_ID_8SVX_EXP: esc->table = exponential; break; default: return -1; } return 0; } AVCodec eightsvx_fib_decoder = { .name = "8svx fibonacci decoder", .type = CODEC_TYPE_AUDIO, .id = CODEC_ID_8SVX_FIB, .priv_data_size = sizeof (EightSvxContext), .init = eightsvx_decode_init, .decode = eightsvx_decode_frame, .long_name = "8SVX fibonacci", }; AVCodec eightsvx_exp_decoder = { .name = "8svx exponential decoder", .type = CODEC_TYPE_AUDIO, .id = CODEC_ID_8SVX_EXP, .priv_data_size = sizeof (EightSvxContext), .init = eightsvx_decode_init, .decode = eightsvx_decode_frame, .long_name = "8SVX exponential", };