1/* 2 * Westwood SNDx codecs 3 * Copyright (c) 2005 Konstantin Shishkov 4 * 5 * This file is part of Libav. 6 * 7 * Libav is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * Libav is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with Libav; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include <stdint.h> 23#include "libavutil/intreadwrite.h" 24#include "avcodec.h" 25 26/** 27 * @file 28 * Westwood SNDx codecs 29 * 30 * Reference documents about VQA format and its audio codecs 31 * can be found here: 32 * http://www.multimedia.cx 33 */ 34 35static const int8_t ws_adpcm_4bit[] = { 36 -9, -8, -6, -5, -4, -3, -2, -1, 37 0, 1, 2, 3, 4, 5, 6, 8 38}; 39 40typedef struct WSSndContext { 41 AVFrame frame; 42} WSSndContext; 43 44static av_cold int ws_snd_decode_init(AVCodecContext *avctx) 45{ 46 WSSndContext *s = avctx->priv_data; 47 48 if (avctx->channels != 1) { 49 av_log_ask_for_sample(avctx, "unsupported number of channels\n"); 50 return AVERROR(EINVAL); 51 } 52 53 avctx->sample_fmt = AV_SAMPLE_FMT_U8; 54 55 avcodec_get_frame_defaults(&s->frame); 56 avctx->coded_frame = &s->frame; 57 58 return 0; 59} 60 61static int ws_snd_decode_frame(AVCodecContext *avctx, void *data, 62 int *got_frame_ptr, AVPacket *avpkt) 63{ 64 WSSndContext *s = avctx->priv_data; 65 const uint8_t *buf = avpkt->data; 66 int buf_size = avpkt->size; 67 68 int in_size, out_size, ret; 69 int sample = 128; 70 uint8_t *samples; 71 uint8_t *samples_end; 72 73 if (!buf_size) 74 return 0; 75 76 if (buf_size < 4) { 77 av_log(avctx, AV_LOG_ERROR, "packet is too small\n"); 78 return AVERROR(EINVAL); 79 } 80 81 out_size = AV_RL16(&buf[0]); 82 in_size = AV_RL16(&buf[2]); 83 buf += 4; 84 85 if (in_size > buf_size) { 86 av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n"); 87 return -1; 88 } 89 90 /* get output buffer */ 91 s->frame.nb_samples = out_size; 92 if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) { 93 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); 94 return ret; 95 } 96 samples = s->frame.data[0]; 97 samples_end = samples + out_size; 98 99 if (in_size == out_size) { 100 memcpy(samples, buf, out_size); 101 *got_frame_ptr = 1; 102 *(AVFrame *)data = s->frame; 103 return buf_size; 104 } 105 106 while (samples < samples_end && buf - avpkt->data < buf_size) { 107 int code, smp, size; 108 uint8_t count; 109 code = *buf >> 6; 110 count = *buf & 0x3F; 111 buf++; 112 113 /* make sure we don't write past the output buffer */ 114 switch (code) { 115 case 0: smp = 4*(count+1); break; 116 case 1: smp = 2*(count+1); break; 117 case 2: smp = (count & 0x20) ? 1 : count + 1; break; 118 default: smp = count + 1; break; 119 } 120 if (samples_end - samples < smp) 121 break; 122 123 /* make sure we don't read past the input buffer */ 124 size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1; 125 if ((buf - avpkt->data) + size > buf_size) 126 break; 127 128 switch (code) { 129 case 0: /* ADPCM 2-bit */ 130 for (count++; count > 0; count--) { 131 code = *buf++; 132 sample += ( code & 0x3) - 2; 133 sample = av_clip_uint8(sample); 134 *samples++ = sample; 135 sample += ((code >> 2) & 0x3) - 2; 136 sample = av_clip_uint8(sample); 137 *samples++ = sample; 138 sample += ((code >> 4) & 0x3) - 2; 139 sample = av_clip_uint8(sample); 140 *samples++ = sample; 141 sample += (code >> 6) - 2; 142 sample = av_clip_uint8(sample); 143 *samples++ = sample; 144 } 145 break; 146 case 1: /* ADPCM 4-bit */ 147 for (count++; count > 0; count--) { 148 code = *buf++; 149 sample += ws_adpcm_4bit[code & 0xF]; 150 sample = av_clip_uint8(sample); 151 *samples++ = sample; 152 sample += ws_adpcm_4bit[code >> 4]; 153 sample = av_clip_uint8(sample); 154 *samples++ = sample; 155 } 156 break; 157 case 2: /* no compression */ 158 if (count & 0x20) { /* big delta */ 159 int8_t t; 160 t = count; 161 t <<= 3; 162 sample += t >> 3; 163 sample = av_clip_uint8(sample); 164 *samples++ = sample; 165 } else { /* copy */ 166 memcpy(samples, buf, smp); 167 samples += smp; 168 buf += smp; 169 sample = buf[-1]; 170 } 171 break; 172 default: /* run */ 173 memset(samples, sample, smp); 174 samples += smp; 175 } 176 } 177 178 s->frame.nb_samples = samples - s->frame.data[0]; 179 *got_frame_ptr = 1; 180 *(AVFrame *)data = s->frame; 181 182 return buf_size; 183} 184 185AVCodec ff_ws_snd1_decoder = { 186 .name = "ws_snd1", 187 .type = AVMEDIA_TYPE_AUDIO, 188 .id = CODEC_ID_WESTWOOD_SND1, 189 .priv_data_size = sizeof(WSSndContext), 190 .init = ws_snd_decode_init, 191 .decode = ws_snd_decode_frame, 192 .capabilities = CODEC_CAP_DR1, 193 .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"), 194}; 195