Libav
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00001 /* 00002 * Westwood SNDx codecs 00003 * Copyright (c) 2005 Konstantin Shishkov 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 00022 #include "libavutil/intreadwrite.h" 00023 #include "avcodec.h" 00024 00034 static const char ws_adpcm_2bit[] = { -2, -1, 0, 1}; 00035 static const char ws_adpcm_4bit[] = { 00036 -9, -8, -6, -5, -4, -3, -2, -1, 00037 0, 1, 2, 3, 4, 5, 6, 8 }; 00038 00039 #define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128; 00040 00041 static av_cold int ws_snd_decode_init(AVCodecContext * avctx) 00042 { 00043 // WSSNDContext *c = avctx->priv_data; 00044 00045 avctx->sample_fmt = SAMPLE_FMT_S16; 00046 return 0; 00047 } 00048 00049 static int ws_snd_decode_frame(AVCodecContext *avctx, 00050 void *data, int *data_size, 00051 AVPacket *avpkt) 00052 { 00053 const uint8_t *buf = avpkt->data; 00054 int buf_size = avpkt->size; 00055 // WSSNDContext *c = avctx->priv_data; 00056 00057 int in_size, out_size; 00058 int sample = 0; 00059 int i; 00060 short *samples = data; 00061 00062 if (!buf_size) 00063 return 0; 00064 00065 out_size = AV_RL16(&buf[0]); 00066 *data_size = out_size * 2; 00067 in_size = AV_RL16(&buf[2]); 00068 buf += 4; 00069 00070 if (out_size > *data_size) { 00071 av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n"); 00072 return -1; 00073 } 00074 if (in_size > buf_size) { 00075 av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); 00076 return -1; 00077 } 00078 if (in_size == out_size) { 00079 for (i = 0; i < out_size; i++) 00080 *samples++ = (*buf++ - 0x80) << 8; 00081 return buf_size; 00082 } 00083 00084 while (out_size > 0) { 00085 int code; 00086 uint8_t count; 00087 code = (*buf) >> 6; 00088 count = (*buf) & 0x3F; 00089 buf++; 00090 switch(code) { 00091 case 0: /* ADPCM 2-bit */ 00092 for (count++; count > 0; count--) { 00093 code = *buf++; 00094 sample += ws_adpcm_2bit[code & 0x3]; 00095 CLIP8(sample); 00096 *samples++ = sample << 8; 00097 sample += ws_adpcm_2bit[(code >> 2) & 0x3]; 00098 CLIP8(sample); 00099 *samples++ = sample << 8; 00100 sample += ws_adpcm_2bit[(code >> 4) & 0x3]; 00101 CLIP8(sample); 00102 *samples++ = sample << 8; 00103 sample += ws_adpcm_2bit[(code >> 6) & 0x3]; 00104 CLIP8(sample); 00105 *samples++ = sample << 8; 00106 out_size -= 4; 00107 } 00108 break; 00109 case 1: /* ADPCM 4-bit */ 00110 for (count++; count > 0; count--) { 00111 code = *buf++; 00112 sample += ws_adpcm_4bit[code & 0xF]; 00113 CLIP8(sample); 00114 *samples++ = sample << 8; 00115 sample += ws_adpcm_4bit[code >> 4]; 00116 CLIP8(sample); 00117 *samples++ = sample << 8; 00118 out_size -= 2; 00119 } 00120 break; 00121 case 2: /* no compression */ 00122 if (count & 0x20) { /* big delta */ 00123 char t; 00124 t = count; 00125 t <<= 3; 00126 sample += t >> 3; 00127 *samples++ = sample << 8; 00128 out_size--; 00129 } else { /* copy */ 00130 for (count++; count > 0; count--) { 00131 *samples++ = (*buf++ - 0x80) << 8; 00132 out_size--; 00133 } 00134 sample = buf[-1] - 0x80; 00135 } 00136 break; 00137 default: /* run */ 00138 for(count++; count > 0; count--) { 00139 *samples++ = sample << 8; 00140 out_size--; 00141 } 00142 } 00143 } 00144 00145 return buf_size; 00146 } 00147 00148 AVCodec ws_snd1_decoder = { 00149 "ws_snd1", 00150 AVMEDIA_TYPE_AUDIO, 00151 CODEC_ID_WESTWOOD_SND1, 00152 0, 00153 ws_snd_decode_init, 00154 NULL, 00155 NULL, 00156 ws_snd_decode_frame, 00157 .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"), 00158 };