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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
*/
/** |
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* @file |
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* Apple MJPEG-B decoder.
*/
#include "avcodec.h"
#include "mjpeg.h"
#include "mjpegdec.h"
|
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static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
uint32_t offs= get_bits_long(gb, 32);
if(offs >= size){
av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
return 0;
}
return offs;
} |
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static int mjpegb_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;
int buf_size = avpkt->size; |
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MJpegDecodeContext *s = avctx->priv_data; |
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const uint8_t *buf_end, *buf_ptr; |
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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; |
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s->got_picture = 0; |
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read_header:
/* reset on every SOI */
s->restart_interval = 0;
s->restart_count = 0;
s->mjpb_skiptosod = 0;
|
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if (buf_end - buf_ptr >= 1 << 28)
return AVERROR_INVALIDDATA;
|
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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"); |
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return AVERROR_INVALIDDATA; |
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}
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 */ |
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second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
|
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dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
if (dqt_offs)
{ |
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init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); |
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s->start_code = DQT; |
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if (ff_mjpeg_decode_dqt(s) < 0 && |
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(avctx->err_recognition & AV_EF_EXPLODE)) |
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return AVERROR_INVALIDDATA; |
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}
|
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dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
if (dht_offs)
{ |
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init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); |
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s->start_code = DHT;
ff_mjpeg_decode_dht(s);
}
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sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
if (sof_offs)
{ |
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init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); |
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s->start_code = SOF0;
if (ff_mjpeg_decode_sof(s) < 0)
return -1;
}
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sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs); |
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sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); |
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av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
if (sos_offs)
{ |
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init_get_bits(&s->gb, buf_ptr + sos_offs,
8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs)); |
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s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
s->start_code = SOS; |
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if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 && |
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(avctx->err_recognition & AV_EF_EXPLODE)) |
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return AVERROR_INVALIDDATA; |
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}
if (s->interlaced) {
s->bottom_field ^= 1;
/* if not bottom field, do not output image yet */ |
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if (s->bottom_field != s->interlace_polarity && second_field_offs) |
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{
buf_ptr = buf + second_field_offs;
goto read_header;
}
}
//XXX FIXME factorize, this looks very similar to the EOI code
|
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*picture= *s->picture_ptr; |
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*data_size = sizeof(AVFrame);
if(!s->lossless){ |
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picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]); |
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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;
}
|
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return buf_size; |
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}
|
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AVCodec ff_mjpegb_decoder = { |
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.name = "mjpegb",
.type = AVMEDIA_TYPE_VIDEO, |
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.id = AV_CODEC_ID_MJPEGB, |
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.priv_data_size = sizeof(MJpegDecodeContext),
.init = ff_mjpeg_decode_init,
.close = ff_mjpeg_decode_end,
.decode = mjpegb_decode_frame,
.capabilities = CODEC_CAP_DR1, |
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.max_lowres = 3, |
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.long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), |
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}; |