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Winnov WNV1 video decoder, courtesy of Konstantin Shishkov
Originally committed as revision 4083 to svn://svn.ffmpeg.org/ffmpeg/trunk
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/* | ||
* Winnov WNV1 codec | ||
* Copyright (c) 2005 Konstantin Shishkov | ||
* | ||
* This library 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 of the License, or (at your option) any later version. | ||
* | ||
* This library 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 this library; if not, write to the Free Software | ||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
* | ||
*/ | ||
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/** | ||
* @file wnv1.c | ||
* Winnov WNV1 codec. | ||
*/ | ||
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#include "avcodec.h" | ||
#include "common.h" | ||
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typedef struct WNV1Context{ | ||
AVCodecContext *avctx; | ||
AVFrame pic; | ||
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int shift; | ||
/* bit buffer */ | ||
unsigned long bitbuf; | ||
int bits; | ||
uint8_t *buf; | ||
} WNV1Context; | ||
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/* returns modified base_value */ | ||
static inline int wnv1_get_code(WNV1Context *w, int base_value) | ||
{ | ||
int v = 0; | ||
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if (w->bits < 16) { /* need to fill bit buffer */ | ||
w->bitbuf |= LE_16(w->buf) << w->bits; | ||
w->buf += 2; | ||
w->bits += 16; | ||
} | ||
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/* escape code */ | ||
if ((w->bitbuf & 0xFF) == 0xFF) { | ||
w->bitbuf >>= 8; | ||
w->bits -= 8; | ||
if (w->bits < 16) { /* need to fill bit buffer */ | ||
w->bitbuf |= LE_16(w->buf) << w->bits; | ||
w->buf += 2; | ||
w->bits += 16; | ||
} | ||
v = w->bitbuf & (0xFF >> w->shift); | ||
w->bitbuf >>= 8 - w->shift; | ||
w->bits -= 8 - w->shift; | ||
return v << w->shift; | ||
} | ||
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/* zero code */ | ||
if (!(w->bitbuf & 1)) { | ||
w->bitbuf >>= 1; | ||
w->bits--; | ||
return base_value; | ||
} | ||
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/* reversed unary code and sign */ | ||
while (w->bits && w->bitbuf & 1) { | ||
w->bitbuf >>= 1; | ||
w->bits--; | ||
v++; | ||
} | ||
w->bitbuf >>= 1; | ||
w->bits--; | ||
if(w->bitbuf & 1) | ||
v = -v; | ||
w->bitbuf >>= 1; | ||
w->bits--; | ||
v <<= w->shift; | ||
return base_value + v; | ||
} | ||
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static int decode_frame(AVCodecContext *avctx, | ||
void *data, int *data_size, | ||
uint8_t *buf, int buf_size) | ||
{ | ||
WNV1Context * const l = avctx->priv_data; | ||
AVFrame * const p= (AVFrame*)&l->pic; | ||
unsigned char *Y,*U,*V; | ||
int i, j; | ||
int prev_y = 0, prev_u = 0, prev_v = 0; | ||
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if(p->data[0]) | ||
avctx->release_buffer(avctx, p); | ||
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p->reference = 0; | ||
if(avctx->get_buffer(avctx, p) < 0){ | ||
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); | ||
return -1; | ||
} | ||
p->key_frame = 1; | ||
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l->bitbuf = 0; | ||
l->bits = 0; | ||
l->buf = buf + 8; | ||
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if (buf[2] >> 4 == 6) | ||
l->shift = 2; | ||
else { | ||
l->shift = 8 - (buf[2] >> 4); | ||
if (l->shift > 4) { | ||
av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4); | ||
l->shift = 4; | ||
} | ||
if (l->shift < 1) { | ||
av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4); | ||
l->shift = 1; | ||
} | ||
} | ||
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Y = p->data[0]; | ||
U = p->data[1]; | ||
V = p->data[2]; | ||
for (j = 0; j < avctx->height; j++) { | ||
for (i = 0; i < avctx->width / 2; i++) { | ||
Y[i * 2] = wnv1_get_code(l, prev_y); | ||
prev_u = U[i] = wnv1_get_code(l, prev_u); | ||
prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]); | ||
prev_v = V[i] = wnv1_get_code(l, prev_v); | ||
} | ||
Y += p->linesize[0]; | ||
U += p->linesize[1]; | ||
V += p->linesize[2]; | ||
} | ||
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*data_size = sizeof(AVFrame); | ||
*(AVFrame*)data = l->pic; | ||
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return buf_size; | ||
} | ||
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static int decode_init(AVCodecContext *avctx){ | ||
WNV1Context * const l = avctx->priv_data; | ||
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l->avctx = avctx; | ||
avctx->pix_fmt = PIX_FMT_YUV422P; | ||
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return 0; | ||
} | ||
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AVCodec wnv1_decoder = { | ||
"wnv1", | ||
CODEC_TYPE_VIDEO, | ||
CODEC_ID_WNV1, | ||
sizeof(WNV1Context), | ||
decode_init, | ||
NULL, | ||
NULL, | ||
decode_frame, | ||
CODEC_CAP_DR1, | ||
}; |
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