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 static av_cold int ws_snd_decode_init(AVCodecContext * avctx) 00041 { 00042 // WSSNDContext *c = avctx->priv_data; 00043 00044 avctx->sample_fmt = AV_SAMPLE_FMT_U8; 00045 return 0; 00046 } 00047 00048 static int ws_snd_decode_frame(AVCodecContext *avctx, 00049 void *data, int *data_size, 00050 AVPacket *avpkt) 00051 { 00052 const uint8_t *buf = avpkt->data; 00053 int buf_size = avpkt->size; 00054 // WSSNDContext *c = avctx->priv_data; 00055 00056 int in_size, out_size; 00057 int sample = 128; 00058 int i; 00059 uint8_t *samples = data; 00060 00061 if (!buf_size) 00062 return 0; 00063 00064 if (buf_size < 4) { 00065 av_log(avctx, AV_LOG_ERROR, "packet is too small\n"); 00066 return AVERROR(EINVAL); 00067 } 00068 00069 out_size = AV_RL16(&buf[0]); 00070 in_size = AV_RL16(&buf[2]); 00071 buf += 4; 00072 00073 if (out_size > *data_size) { 00074 av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n"); 00075 return -1; 00076 } 00077 if (in_size > buf_size) { 00078 av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); 00079 return -1; 00080 } 00081 00082 if (in_size == out_size) { 00083 for (i = 0; i < out_size; i++) 00084 *samples++ = *buf++; 00085 *data_size = out_size; 00086 return buf_size; 00087 } 00088 00089 while (out_size > 0 && buf - avpkt->data < buf_size) { 00090 int code, smp, size; 00091 uint8_t count; 00092 code = (*buf) >> 6; 00093 count = (*buf) & 0x3F; 00094 buf++; 00095 00096 /* make sure we don't write more than out_size samples */ 00097 switch (code) { 00098 case 0: smp = 4*(count+1); break; 00099 case 1: smp = 2*(count+1); break; 00100 case 2: smp = (count & 0x20) ? 1 : count + 1; break; 00101 default: smp = count + 1; break; 00102 } 00103 if (out_size < smp) { 00104 out_size = 0; 00105 break; 00106 } 00107 00108 /* make sure we don't read past the input buffer */ 00109 size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1; 00110 if ((buf - avpkt->data) + size > buf_size) 00111 break; 00112 00113 switch(code) { 00114 case 0: /* ADPCM 2-bit */ 00115 for (count++; count > 0; count--) { 00116 code = *buf++; 00117 sample += ws_adpcm_2bit[code & 0x3]; 00118 sample = av_clip_uint8(sample); 00119 *samples++ = sample; 00120 sample += ws_adpcm_2bit[(code >> 2) & 0x3]; 00121 sample = av_clip_uint8(sample); 00122 *samples++ = sample; 00123 sample += ws_adpcm_2bit[(code >> 4) & 0x3]; 00124 sample = av_clip_uint8(sample); 00125 *samples++ = sample; 00126 sample += ws_adpcm_2bit[(code >> 6) & 0x3]; 00127 sample = av_clip_uint8(sample); 00128 *samples++ = sample; 00129 out_size -= 4; 00130 } 00131 break; 00132 case 1: /* ADPCM 4-bit */ 00133 for (count++; count > 0; count--) { 00134 code = *buf++; 00135 sample += ws_adpcm_4bit[code & 0xF]; 00136 sample = av_clip_uint8(sample); 00137 *samples++ = sample; 00138 sample += ws_adpcm_4bit[code >> 4]; 00139 sample = av_clip_uint8(sample); 00140 *samples++ = sample; 00141 out_size -= 2; 00142 } 00143 break; 00144 case 2: /* no compression */ 00145 if (count & 0x20) { /* big delta */ 00146 int8_t t; 00147 t = count; 00148 t <<= 3; 00149 sample += t >> 3; 00150 sample = av_clip_uint8(sample); 00151 *samples++ = sample; 00152 out_size--; 00153 } else { /* copy */ 00154 for (count++; count > 0; count--) { 00155 *samples++ = *buf++; 00156 out_size--; 00157 } 00158 sample = buf[-1]; 00159 } 00160 break; 00161 default: /* run */ 00162 for(count++; count > 0; count--) { 00163 *samples++ = sample; 00164 out_size--; 00165 } 00166 } 00167 } 00168 00169 *data_size = samples - (uint8_t *)data; 00170 00171 return buf_size; 00172 } 00173 00174 AVCodec ff_ws_snd1_decoder = { 00175 "ws_snd1", 00176 AVMEDIA_TYPE_AUDIO, 00177 CODEC_ID_WESTWOOD_SND1, 00178 0, 00179 ws_snd_decode_init, 00180 NULL, 00181 NULL, 00182 ws_snd_decode_frame, 00183 .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"), 00184 };