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/*
* Apple MJPEG-B decoder
* Copyright (c) 2002 Alex Beregszaszi
*
* 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 mjpegbdec.c
* Apple MJPEG-B decoder.
*/
#include "avcodec.h"
#include "mjpeg.h"
#include "mjpegdec.h"
static int mjpegb_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
const uint8_t *buf, int buf_size)
{
MJpegDecodeContext *s = avctx->priv_data;
const uint8_t *buf_end, *buf_ptr;
AVFrame *picture = data;
GetBitContext hgb; /* for the header */
uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
uint32_t field_size, sod_offs;
buf_ptr = buf;
buf_end = buf + buf_size;
read_header:
/* reset on every SOI */
s->restart_interval = 0;
s->restart_count = 0;
s->mjpb_skiptosod = 0;
init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
skip_bits(&hgb, 32); /* reserved zeros */
if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
{
av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
return 0;
}
field_size = get_bits_long(&hgb, 32); /* field size */
av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
skip_bits(&hgb, 32); /* padded field size */
second_field_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
dqt_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
if (dqt_offs)
{
init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
s->start_code = DQT;
ff_mjpeg_decode_dqt(s);
}
dht_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
if (dht_offs)
{
init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
s->start_code = DHT;
ff_mjpeg_decode_dht(s);
}
sof_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
if (sof_offs)
{
init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
s->start_code = SOF0;
if (ff_mjpeg_decode_sof(s) < 0)
return -1;
}
sos_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
sod_offs = get_bits_long(&hgb, 32);
av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
if (sos_offs)
{
// init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
s->start_code = SOS;
ff_mjpeg_decode_sos(s);
}
if (s->interlaced) {
s->bottom_field ^= 1;
/* if not bottom field, do not output image yet */
if (s->bottom_field != s->interlace_polarity && second_field_offs)
{
buf_ptr = buf + second_field_offs;
second_field_offs = 0;
goto read_header;
}
}
//XXX FIXME factorize, this looks very similar to the EOI code
*picture= s->picture;
*data_size = sizeof(AVFrame);
if(!s->lossless){
picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
picture->qstride= 0;
picture->qscale_table= s->qscale_table;
memset(picture->qscale_table, picture->quality, (s->width+15)/16);
if(avctx->debug & FF_DEBUG_QP)
av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
picture->quality*= FF_QP2LAMBDA;
}
return buf_ptr - buf;
}
AVCodec mjpegb_decoder = {
"mjpegb",
CODEC_TYPE_VIDEO,
CODEC_ID_MJPEGB,
sizeof(MJpegDecodeContext),
ff_mjpeg_decode_init,
NULL,
ff_mjpeg_decode_end,
mjpegb_decode_frame,
CODEC_CAP_DR1,
NULL
};
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