• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavcodec/ws-snd1.c

Go to the documentation of this file.
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                 const uint8_t *buf, int buf_size)
00052 {
00053 //    WSSNDContext *c = avctx->priv_data;
00054 
00055     int in_size, out_size;
00056     int sample = 0;
00057     int i;
00058     short *samples = data;
00059 
00060     if (!buf_size)
00061         return 0;
00062 
00063     out_size = AV_RL16(&buf[0]);
00064     *data_size = out_size * 2;
00065     in_size = AV_RL16(&buf[2]);
00066     buf += 4;
00067 
00068     if (out_size > *data_size) {
00069         av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
00070         return -1;
00071     }
00072     if (in_size > buf_size) {
00073         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
00074         return -1;
00075     }
00076     if (in_size == out_size) {
00077         for (i = 0; i < out_size; i++)
00078             *samples++ = (*buf++ - 0x80) << 8;
00079         return buf_size;
00080     }
00081 
00082     while (out_size > 0) {
00083         int code;
00084         uint8_t count;
00085         code = (*buf) >> 6;
00086         count = (*buf) & 0x3F;
00087         buf++;
00088         switch(code) {
00089         case 0: /* ADPCM 2-bit */
00090             for (count++; count > 0; count--) {
00091                 code = *buf++;
00092                 sample += ws_adpcm_2bit[code & 0x3];
00093                 CLIP8(sample);
00094                 *samples++ = sample << 8;
00095                 sample += ws_adpcm_2bit[(code >> 2) & 0x3];
00096                 CLIP8(sample);
00097                 *samples++ = sample << 8;
00098                 sample += ws_adpcm_2bit[(code >> 4) & 0x3];
00099                 CLIP8(sample);
00100                 *samples++ = sample << 8;
00101                 sample += ws_adpcm_2bit[(code >> 6) & 0x3];
00102                 CLIP8(sample);
00103                 *samples++ = sample << 8;
00104                 out_size -= 4;
00105             }
00106             break;
00107         case 1: /* ADPCM 4-bit */
00108             for (count++; count > 0; count--) {
00109                 code = *buf++;
00110                 sample += ws_adpcm_4bit[code & 0xF];
00111                 CLIP8(sample);
00112                 *samples++ = sample << 8;
00113                 sample += ws_adpcm_4bit[code >> 4];
00114                 CLIP8(sample);
00115                 *samples++ = sample << 8;
00116                 out_size -= 2;
00117             }
00118             break;
00119         case 2: /* no compression */
00120             if (count & 0x20) { /* big delta */
00121                 char t;
00122                 t = count;
00123                 t <<= 3;
00124                 sample += t >> 3;
00125                 *samples++ = sample << 8;
00126                 out_size--;
00127             } else { /* copy */
00128                 for (count++; count > 0; count--) {
00129                     *samples++ = (*buf++ - 0x80) << 8;
00130                     out_size--;
00131                 }
00132                 sample = buf[-1] - 0x80;
00133             }
00134             break;
00135         default: /* run */
00136             for(count++; count > 0; count--) {
00137                 *samples++ = sample << 8;
00138                 out_size--;
00139             }
00140         }
00141     }
00142 
00143     return buf_size;
00144 }
00145 
00146 AVCodec ws_snd1_decoder = {
00147     "ws_snd1",
00148     CODEC_TYPE_AUDIO,
00149     CODEC_ID_WESTWOOD_SND1,
00150     0,
00151     ws_snd_decode_init,
00152     NULL,
00153     NULL,
00154     ws_snd_decode_frame,
00155     .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
00156 };

Generated on Tue Nov 4 2014 12:59:23 for ffmpeg by  doxygen 1.7.1