1/* 2 * 8SVX audio decoder 3 * Copyright (C) 2008 Jaikrishnan Menon 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/** 23 * @file 24 * 8svx audio decoder 25 * @author Jaikrishnan Menon 26 * 27 * supports: fibonacci delta encoding 28 * : exponential encoding 29 */ 30 31#include "avcodec.h" 32 33/** decoder context */ 34typedef struct EightSvxContext { 35 AVFrame frame; 36 uint8_t fib_acc[2]; 37 const int8_t *table; 38 39 /* buffer used to store the whole first packet. 40 data is only sent as one large packet */ 41 uint8_t *data[2]; 42 int data_size; 43 int data_idx; 44} EightSvxContext; 45 46static const int8_t fibonacci[16] = { -34, -21, -13, -8, -5, -3, -2, -1, 47 0, 1, 2, 3, 5, 8, 13, 21 }; 48static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1, 49 0, 1, 2, 4, 8, 16, 32, 64 }; 50 51#define MAX_FRAME_SIZE 32768 52 53/** 54 * Delta decode the compressed values in src, and put the resulting 55 * decoded samples in dst. 56 * 57 * @param[in,out] state starting value. it is saved for use in the next call. 58 */ 59static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size, 60 uint8_t *state, const int8_t *table, int channels) 61{ 62 uint8_t val = *state; 63 64 while (src_size--) { 65 uint8_t d = *src++; 66 val = av_clip_uint8(val + table[d & 0xF]); 67 *dst = val; 68 dst += channels; 69 val = av_clip_uint8(val + table[d >> 4]); 70 *dst = val; 71 dst += channels; 72 } 73 74 *state = val; 75} 76 77static void raw_decode(uint8_t *dst, const int8_t *src, int src_size, 78 int channels) 79{ 80 while (src_size--) { 81 *dst = *src++ + 128; 82 dst += channels; 83 } 84} 85 86/** decode a frame */ 87static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, 88 int *got_frame_ptr, AVPacket *avpkt) 89{ 90 EightSvxContext *esc = avctx->priv_data; 91 int buf_size; 92 uint8_t *out_data; 93 int ret; 94 int is_compr = (avctx->codec_id != CODEC_ID_PCM_S8_PLANAR); 95 96 /* for the first packet, copy data to buffer */ 97 if (avpkt->data) { 98 int hdr_size = is_compr ? 2 : 0; 99 int chan_size = (avpkt->size - hdr_size * avctx->channels) / avctx->channels; 100 101 if (avpkt->size < hdr_size * avctx->channels) { 102 av_log(avctx, AV_LOG_ERROR, "packet size is too small\n"); 103 return AVERROR(EINVAL); 104 } 105 if (esc->data[0]) { 106 av_log(avctx, AV_LOG_ERROR, "unexpected data after first packet\n"); 107 return AVERROR(EINVAL); 108 } 109 110 if (is_compr) { 111 esc->fib_acc[0] = avpkt->data[1] + 128; 112 if (avctx->channels == 2) 113 esc->fib_acc[1] = avpkt->data[2+chan_size+1] + 128; 114 } 115 116 esc->data_idx = 0; 117 esc->data_size = chan_size; 118 if (!(esc->data[0] = av_malloc(chan_size))) 119 return AVERROR(ENOMEM); 120 if (avctx->channels == 2) { 121 if (!(esc->data[1] = av_malloc(chan_size))) { 122 av_freep(&esc->data[0]); 123 return AVERROR(ENOMEM); 124 } 125 } 126 memcpy(esc->data[0], &avpkt->data[hdr_size], chan_size); 127 if (avctx->channels == 2) 128 memcpy(esc->data[1], &avpkt->data[2*hdr_size+chan_size], chan_size); 129 } 130 if (!esc->data[0]) { 131 av_log(avctx, AV_LOG_ERROR, "unexpected empty packet\n"); 132 return AVERROR(EINVAL); 133 } 134 135 /* decode next piece of data from the buffer */ 136 buf_size = FFMIN(MAX_FRAME_SIZE, esc->data_size - esc->data_idx); 137 if (buf_size <= 0) { 138 *got_frame_ptr = 0; 139 return avpkt->size; 140 } 141 142 /* get output buffer */ 143 esc->frame.nb_samples = buf_size * (is_compr + 1); 144 if ((ret = avctx->get_buffer(avctx, &esc->frame)) < 0) { 145 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); 146 return ret; 147 } 148 out_data = esc->frame.data[0]; 149 150 if (is_compr) { 151 delta_decode(out_data, &esc->data[0][esc->data_idx], buf_size, 152 &esc->fib_acc[0], esc->table, avctx->channels); 153 if (avctx->channels == 2) { 154 delta_decode(&out_data[1], &esc->data[1][esc->data_idx], buf_size, 155 &esc->fib_acc[1], esc->table, avctx->channels); 156 } 157 } else { 158 int ch; 159 for (ch = 0; ch < avctx->channels; ch++) { 160 raw_decode((int8_t *)&out_data[ch], &esc->data[ch][esc->data_idx], 161 buf_size, avctx->channels); 162 } 163 } 164 esc->data_idx += buf_size; 165 166 *got_frame_ptr = 1; 167 *(AVFrame *)data = esc->frame; 168 169 return avpkt->size; 170} 171 172/** initialize 8svx decoder */ 173static av_cold int eightsvx_decode_init(AVCodecContext *avctx) 174{ 175 EightSvxContext *esc = avctx->priv_data; 176 177 if (avctx->channels < 1 || avctx->channels > 2) { 178 av_log(avctx, AV_LOG_ERROR, "8SVX does not support more than 2 channels\n"); 179 return AVERROR(EINVAL); 180 } 181 182 switch(avctx->codec->id) { 183 case CODEC_ID_8SVX_FIB: 184 esc->table = fibonacci; 185 break; 186 case CODEC_ID_8SVX_EXP: 187 esc->table = exponential; 188 break; 189 case CODEC_ID_PCM_S8_PLANAR: 190 break; 191 default: 192 return -1; 193 } 194 avctx->sample_fmt = AV_SAMPLE_FMT_U8; 195 196 avcodec_get_frame_defaults(&esc->frame); 197 avctx->coded_frame = &esc->frame; 198 199 return 0; 200} 201 202static av_cold int eightsvx_decode_close(AVCodecContext *avctx) 203{ 204 EightSvxContext *esc = avctx->priv_data; 205 206 av_freep(&esc->data[0]); 207 av_freep(&esc->data[1]); 208 209 return 0; 210} 211 212AVCodec ff_eightsvx_fib_decoder = { 213 .name = "8svx_fib", 214 .type = AVMEDIA_TYPE_AUDIO, 215 .id = CODEC_ID_8SVX_FIB, 216 .priv_data_size = sizeof (EightSvxContext), 217 .init = eightsvx_decode_init, 218 .close = eightsvx_decode_close, 219 .decode = eightsvx_decode_frame, 220 .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, 221 .long_name = NULL_IF_CONFIG_SMALL("8SVX fibonacci"), 222}; 223 224AVCodec ff_eightsvx_exp_decoder = { 225 .name = "8svx_exp", 226 .type = AVMEDIA_TYPE_AUDIO, 227 .id = CODEC_ID_8SVX_EXP, 228 .priv_data_size = sizeof (EightSvxContext), 229 .init = eightsvx_decode_init, 230 .close = eightsvx_decode_close, 231 .decode = eightsvx_decode_frame, 232 .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, 233 .long_name = NULL_IF_CONFIG_SMALL("8SVX exponential"), 234}; 235 236AVCodec ff_pcm_s8_planar_decoder = { 237 .name = "pcm_s8_planar", 238 .type = AVMEDIA_TYPE_AUDIO, 239 .id = CODEC_ID_PCM_S8_PLANAR, 240 .priv_data_size = sizeof(EightSvxContext), 241 .init = eightsvx_decode_init, 242 .close = eightsvx_decode_close, 243 .decode = eightsvx_decode_frame, 244 .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1, 245 .long_name = NULL_IF_CONFIG_SMALL("PCM signed 8-bit planar"), 246}; 247