diff options
author | Jai Menon <realityman@gmx.net> | 2008-03-30 23:16:08 +0400 |
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committer | Vitor Sessak <vitor1001@gmail.com> | 2008-03-30 23:16:08 +0400 |
commit | cb21e0a7155028ebb05cd576ec9827c52613a317 (patch) | |
tree | 9f5fcca4e7d3dd346ad530dc6ec811504161d112 /libavcodec/8svx.c | |
parent | e516d3488ab46823389113aec5386eb5e4365d64 (diff) |
8SVX decoder
Patch by Jai Menon (realityman <at> gmx.net)
Originally committed as revision 12632 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/8svx.c')
-rw-r--r-- | libavcodec/8svx.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/libavcodec/8svx.c b/libavcodec/8svx.c new file mode 100644 index 0000000000..1c98a7ec74 --- /dev/null +++ b/libavcodec/8svx.c @@ -0,0 +1,114 @@ +/* + * 8SVX Audio Decoder + * Copyright (C) 2008 Jaikrishnan Menon + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file 8svx.c + * 8svx audio decoder + * @author Jaikrishnan Menon + * supports: fibonacci delta encoding + * : exponential encoding + */ + +#include "avcodec.h" + +/** + * decoder context + */ +typedef struct EightSvxContext { + int16_t fib_acc; + int16_t *table; +} EightSvxContext; + +const static int16_t fibonacci[16] = { -34<<8, -21<<8, -13<<8, -8<<8, -5<<8, -3<<8, -2<<8, -1<<8, + 0, 1<<8, 2<<8, 3<<8, 5<<8, 8<<8, 13<<8, 21<<8 }; +const static int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8, -8<<8, -4<<8, -2<<8, -1<<8, + 0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8, 32<<8, 64<<8 }; + +/** + * decode a frame + */ +static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size, + const uint8_t *buf, int buf_size) +{ + EightSvxContext *esc = avctx->priv_data; + int16_t *out_data = data; + int consumed = buf_size; + const uint8_t *buf_end = buf + buf_size; + + if((*data_size >> 2) < buf_size) + return -1; + + if(avctx->frame_number == 0) { + esc->fib_acc = buf[1] << 8; + buf_size -= 2; + buf += 2; + } + + *data_size = buf_size << 2; + + while(buf < buf_end) { + uint8_t d = *buf++; + esc->fib_acc += esc->table[d & 0x0f]; + *out_data++ = esc->fib_acc; + esc->fib_acc += esc->table[d >> 4]; + *out_data++ = esc->fib_acc; + } + + return consumed; +} + +/** + * initialize 8svx decoder + */ +static av_cold int eightsvx_decode_init(AVCodecContext *avctx) +{ + EightSvxContext *esc = avctx->priv_data; + + switch(avctx->codec->id) { + case CODEC_ID_8SVX_FIB: + esc->table = fibonacci; + break; + case CODEC_ID_8SVX_EXP: + esc->table = exponential; + break; + default: + return -1; + } + return 0; +} + +AVCodec eightsvx_fib_decoder = { + .name = "8svx fibonacci decoder", + .type = CODEC_TYPE_AUDIO, + .id = CODEC_ID_8SVX_FIB, + .priv_data_size = sizeof (EightSvxContext), + .init = eightsvx_decode_init, + .decode = eightsvx_decode_frame, +}; + +AVCodec eightsvx_exp_decoder = { + .name = "8svx exponential decoder", + .type = CODEC_TYPE_AUDIO, + .id = CODEC_ID_8SVX_EXP, + .priv_data_size = sizeof (EightSvxContext), + .init = eightsvx_decode_init, + .decode = eightsvx_decode_frame, +}; |