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137 lines
4.0 KiB
C
137 lines
4.0 KiB
C
/*
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* 8SVX audio decoder
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* Copyright (C) 2008 Jaikrishnan Menon
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* 8svx audio decoder
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* @author Jaikrishnan Menon
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*
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* supports: fibonacci delta encoding
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* : exponential encoding
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*/
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#include "avcodec.h"
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/** decoder context */
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typedef struct EightSvxContext {
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uint8_t fib_acc;
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const int8_t *table;
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} EightSvxContext;
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static const int8_t fibonacci[16] = { -34, -21, -13, -8, -5, -3, -2, -1,
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0, 1, 2, 3, 5, 8, 13, 21 };
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static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1,
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0, 1, 2, 4, 8, 16, 32, 64 };
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/**
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* Delta decode the compressed values in src, and put the resulting
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* decoded samples in dst.
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*
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* @param[in,out] state starting value. it is saved for use in the next call.
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*/
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static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size,
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uint8_t *state, const int8_t *table)
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{
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uint8_t val = *state;
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while (src_size--) {
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uint8_t d = *src++;
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val = av_clip_uint8(val + table[d & 0xF]);
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*dst++ = val;
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val = av_clip_uint8(val + table[d >> 4]);
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*dst++ = val;
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}
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*state = val;
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}
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/** decode a frame */
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static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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AVPacket *avpkt)
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{
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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EightSvxContext *esc = avctx->priv_data;
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uint8_t *out_data = data;
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int consumed = buf_size;
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if(avctx->frame_number == 0) {
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if (buf_size < 2) {
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av_log(avctx, AV_LOG_ERROR, "packet size is too small\n");
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return AVERROR(EINVAL);
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}
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esc->fib_acc = (int8_t)buf[1] + 128;
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buf_size -= 2;
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buf += 2;
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}
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if (*data_size < buf_size * 2) {
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av_log(avctx, AV_LOG_ERROR, "Provided buffer with size %d is too small.\n",
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*data_size);
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return AVERROR(EINVAL);
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}
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delta_decode(out_data, buf, buf_size, &esc->fib_acc, esc->table);
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*data_size = buf_size * 2;
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return consumed;
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}
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/** initialize 8svx decoder */
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static av_cold int eightsvx_decode_init(AVCodecContext *avctx)
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{
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EightSvxContext *esc = avctx->priv_data;
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switch(avctx->codec->id) {
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case CODEC_ID_8SVX_FIB:
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esc->table = fibonacci;
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break;
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case CODEC_ID_8SVX_EXP:
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esc->table = exponential;
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break;
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default:
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return -1;
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}
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avctx->sample_fmt = AV_SAMPLE_FMT_U8;
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return 0;
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}
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AVCodec ff_eightsvx_fib_decoder = {
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.name = "8svx_fib",
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.type = AVMEDIA_TYPE_AUDIO,
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.id = CODEC_ID_8SVX_FIB,
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.priv_data_size = sizeof (EightSvxContext),
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.init = eightsvx_decode_init,
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.decode = eightsvx_decode_frame,
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.long_name = NULL_IF_CONFIG_SMALL("8SVX fibonacci"),
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};
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AVCodec ff_eightsvx_exp_decoder = {
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.name = "8svx_exp",
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.type = AVMEDIA_TYPE_AUDIO,
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.id = CODEC_ID_8SVX_EXP,
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.priv_data_size = sizeof (EightSvxContext),
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.init = eightsvx_decode_init,
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.decode = eightsvx_decode_frame,
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.long_name = NULL_IF_CONFIG_SMALL("8SVX exponential"),
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};
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