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/*****************************************************************************
* mxpeg_helper.h: MXPEG helper functions
*****************************************************************************
* Copyright (C) 2012 VLC authors and VideoLAN
* $Id: a8f6e2e994dc3bf5bbe30d9cb421c11ad0c29b64 $
*
* Authors: Sébastien Escudier
*
* This program 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.
*
* This program 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 program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
/**
* Finds FF XX in the first size byte of data
*/
static uint8_t find_jpeg_marker(int *position, const uint8_t *data, int size)
{
for (int i = *position; i + 1 < size; i++) {
if (data[i] != 0xff)
continue;
if (data[i + 1] != 0xff) {
*position = i + 2;
return data[i + 1];
}
}
return 0xff;
}
/*
* Mxpeg frame format : http://developer.mobotix.com/docs/mxpeg_frame.html
* */
static bool IsMxpeg(stream_t *s)
{
const uint8_t *header;
int size = stream_Peek(s, &header, 256);
int position = 0;
if (find_jpeg_marker(&position, header, size) != 0xd8 || position > size-2)
return false;
if (find_jpeg_marker(&position, header, position + 2) != 0xe0)
return false;
if (position + 2 > size)
return false;
/* Skip this jpeg header */
uint32_t header_size = GetWBE(&header[position]);
position += header_size;
/* Get enough data to analyse the next header */
if (position + 6 > size)
{
size = position + 6;
if( stream_Peek (s, &header, size) < size )
return false;
}
if ( !(header[position] == 0xFF && header[position+1] == 0xFE) )
return false;
position += 2;
header_size = GetWBE (&header[position]);
/* Check if this is a MXF header. We may have a jpeg comment first */
if (!memcmp (&header[position+2], "MXF\0", 4) )
return true;
/* Skip the jpeg comment and find the MXF header after that */
size = position + header_size + 8; //8 = FF FE 00 00 M X F 00
if (stream_Peek(s, &header, size ) < size)
return false;
position += header_size;
if ( !(header[position] == 0xFF && header[position+1] == 0xFE) )
return false;
position += 4;
if (memcmp (&header[position], "MXF\0", 4) )
return false;
return true;
}
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