00001 /* 00002 * 8SVX audio decoder 00003 * Copyright (C) 2008 Jaikrishnan Menon 00004 * 00005 * This file is part of FFmpeg. 00006 * 00007 * FFmpeg is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * FFmpeg is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with FFmpeg; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00030 #include "avcodec.h" 00031 00033 typedef struct EightSvxContext { 00034 int16_t fib_acc; 00035 const int16_t *table; 00036 } EightSvxContext; 00037 00038 static const int16_t fibonacci[16] = { -34<<8, -21<<8, -13<<8, -8<<8, -5<<8, -3<<8, -2<<8, -1<<8, 00039 0, 1<<8, 2<<8, 3<<8, 5<<8, 8<<8, 13<<8, 21<<8 }; 00040 static const int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8, -8<<8, -4<<8, -2<<8, -1<<8, 00041 0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8, 32<<8, 64<<8 }; 00042 00044 static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size, 00045 const uint8_t *buf, int buf_size) 00046 { 00047 EightSvxContext *esc = avctx->priv_data; 00048 int16_t *out_data = data; 00049 int consumed = buf_size; 00050 const uint8_t *buf_end = buf + buf_size; 00051 00052 if((*data_size >> 2) < buf_size) 00053 return -1; 00054 00055 if(avctx->frame_number == 0) { 00056 esc->fib_acc = buf[1] << 8; 00057 buf_size -= 2; 00058 buf += 2; 00059 } 00060 00061 *data_size = buf_size << 2; 00062 00063 while(buf < buf_end) { 00064 uint8_t d = *buf++; 00065 esc->fib_acc += esc->table[d & 0x0f]; 00066 *out_data++ = esc->fib_acc; 00067 esc->fib_acc += esc->table[d >> 4]; 00068 *out_data++ = esc->fib_acc; 00069 } 00070 00071 return consumed; 00072 } 00073 00075 static av_cold int eightsvx_decode_init(AVCodecContext *avctx) 00076 { 00077 EightSvxContext *esc = avctx->priv_data; 00078 00079 switch(avctx->codec->id) { 00080 case CODEC_ID_8SVX_FIB: 00081 esc->table = fibonacci; 00082 break; 00083 case CODEC_ID_8SVX_EXP: 00084 esc->table = exponential; 00085 break; 00086 default: 00087 return -1; 00088 } 00089 avctx->sample_fmt = SAMPLE_FMT_S16; 00090 return 0; 00091 } 00092 00093 AVCodec eightsvx_fib_decoder = { 00094 .name = "8svx_fib", 00095 .type = CODEC_TYPE_AUDIO, 00096 .id = CODEC_ID_8SVX_FIB, 00097 .priv_data_size = sizeof (EightSvxContext), 00098 .init = eightsvx_decode_init, 00099 .decode = eightsvx_decode_frame, 00100 .long_name = NULL_IF_CONFIG_SMALL("8SVX fibonacci"), 00101 }; 00102 00103 AVCodec eightsvx_exp_decoder = { 00104 .name = "8svx_exp", 00105 .type = CODEC_TYPE_AUDIO, 00106 .id = CODEC_ID_8SVX_EXP, 00107 .priv_data_size = sizeof (EightSvxContext), 00108 .init = eightsvx_decode_init, 00109 .decode = eightsvx_decode_frame, 00110 .long_name = NULL_IF_CONFIG_SMALL("8SVX exponential"), 00111 };