Libav 0.7.1
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00001 /* 00002 * Westwood SNDx codecs 00003 * Copyright (c) 2005 Konstantin Shishkov 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00022 #include <stdint.h> 00023 #include "libavutil/intreadwrite.h" 00024 #include "avcodec.h" 00025 00035 static const int8_t ws_adpcm_2bit[] = { -2, -1, 0, 1}; 00036 static const int8_t ws_adpcm_4bit[] = { 00037 -9, -8, -6, -5, -4, -3, -2, -1, 00038 0, 1, 2, 3, 4, 5, 6, 8 }; 00039 00040 #define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128; 00041 00042 static av_cold int ws_snd_decode_init(AVCodecContext * avctx) 00043 { 00044 // WSSNDContext *c = avctx->priv_data; 00045 00046 avctx->sample_fmt = AV_SAMPLE_FMT_S16; 00047 return 0; 00048 } 00049 00050 static int ws_snd_decode_frame(AVCodecContext *avctx, 00051 void *data, int *data_size, 00052 AVPacket *avpkt) 00053 { 00054 const uint8_t *buf = avpkt->data; 00055 int buf_size = avpkt->size; 00056 // WSSNDContext *c = avctx->priv_data; 00057 00058 int in_size, out_size; 00059 int sample = 0; 00060 int i; 00061 short *samples = data; 00062 00063 if (!buf_size) 00064 return 0; 00065 00066 out_size = AV_RL16(&buf[0]); 00067 *data_size = out_size * 2; 00068 in_size = AV_RL16(&buf[2]); 00069 buf += 4; 00070 00071 if (out_size > *data_size) { 00072 av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n"); 00073 return -1; 00074 } 00075 if (in_size > buf_size) { 00076 av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); 00077 return -1; 00078 } 00079 if (in_size == out_size) { 00080 for (i = 0; i < out_size; i++) 00081 *samples++ = (*buf++ - 0x80) << 8; 00082 return buf_size; 00083 } 00084 00085 while (out_size > 0) { 00086 int code; 00087 uint8_t count; 00088 code = (*buf) >> 6; 00089 count = (*buf) & 0x3F; 00090 buf++; 00091 switch(code) { 00092 case 0: /* ADPCM 2-bit */ 00093 for (count++; count > 0; count--) { 00094 code = *buf++; 00095 sample += ws_adpcm_2bit[code & 0x3]; 00096 CLIP8(sample); 00097 *samples++ = sample << 8; 00098 sample += ws_adpcm_2bit[(code >> 2) & 0x3]; 00099 CLIP8(sample); 00100 *samples++ = sample << 8; 00101 sample += ws_adpcm_2bit[(code >> 4) & 0x3]; 00102 CLIP8(sample); 00103 *samples++ = sample << 8; 00104 sample += ws_adpcm_2bit[(code >> 6) & 0x3]; 00105 CLIP8(sample); 00106 *samples++ = sample << 8; 00107 out_size -= 4; 00108 } 00109 break; 00110 case 1: /* ADPCM 4-bit */ 00111 for (count++; count > 0; count--) { 00112 code = *buf++; 00113 sample += ws_adpcm_4bit[code & 0xF]; 00114 CLIP8(sample); 00115 *samples++ = sample << 8; 00116 sample += ws_adpcm_4bit[code >> 4]; 00117 CLIP8(sample); 00118 *samples++ = sample << 8; 00119 out_size -= 2; 00120 } 00121 break; 00122 case 2: /* no compression */ 00123 if (count & 0x20) { /* big delta */ 00124 int8_t t; 00125 t = count; 00126 t <<= 3; 00127 sample += t >> 3; 00128 *samples++ = sample << 8; 00129 out_size--; 00130 } else { /* copy */ 00131 for (count++; count > 0; count--) { 00132 *samples++ = (*buf++ - 0x80) << 8; 00133 out_size--; 00134 } 00135 sample = buf[-1] - 0x80; 00136 } 00137 break; 00138 default: /* run */ 00139 for(count++; count > 0; count--) { 00140 *samples++ = sample << 8; 00141 out_size--; 00142 } 00143 } 00144 } 00145 00146 return buf_size; 00147 } 00148 00149 AVCodec ff_ws_snd1_decoder = { 00150 "ws_snd1", 00151 AVMEDIA_TYPE_AUDIO, 00152 CODEC_ID_WESTWOOD_SND1, 00153 0, 00154 ws_snd_decode_init, 00155 NULL, 00156 NULL, 00157 ws_snd_decode_frame, 00158 .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"), 00159 };