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92 lines
2.9 KiB
92 lines
2.9 KiB
/*****************************************************************************
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* mxpeg_helper.h: MXPEG helper functions
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*****************************************************************************
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* Copyright (C) 2012 VLC authors and VideoLAN
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*
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* Authors: Sébastien Escudier
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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/**
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* Finds FF XX in the first size byte of data
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*/
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static uint8_t find_jpeg_marker(int *position, const uint8_t *data, int size)
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{
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for (int i = *position; i + 1 < size; i++) {
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if (data[i] != 0xff)
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continue;
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if (data[i + 1] != 0xff) {
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*position = i + 2;
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return data[i + 1];
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}
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}
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return 0xff;
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}
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/*
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* Mxpeg frame format : http://developer.mobotix.com/docs/mxpeg_frame.html
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* */
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static bool IsMxpeg(stream_t *s)
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{
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const uint8_t *header;
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int size = vlc_stream_Peek(s, &header, 256);
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int position = 0;
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if (find_jpeg_marker(&position, header, size) != 0xd8 || position > size-2)
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return false;
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if (find_jpeg_marker(&position, header, position + 2) != 0xe0)
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return false;
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if (position + 2 > size)
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return false;
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/* Skip this jpeg header */
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uint32_t header_size = GetWBE(&header[position]);
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position += header_size;
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/* Get enough data to analyse the next header */
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if (position + 6 > size)
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{
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size = position + 6;
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if( vlc_stream_Peek (s, &header, size) < size )
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return false;
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}
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if ( !(header[position] == 0xFF && header[position+1] == 0xFE) )
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return false;
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position += 2;
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header_size = GetWBE (&header[position]);
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/* Check if this is a MXF header. We may have a jpeg comment first */
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if (!memcmp (&header[position+2], "MXF\0", 4) )
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return true;
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/* Skip the jpeg comment and find the MXF header after that */
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size = position + header_size + 8; //8 = FF FE 00 00 M X F 00
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if (vlc_stream_Peek(s, &header, size ) < size)
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return false;
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position += header_size;
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if ( !(header[position] == 0xFF && header[position+1] == 0xFE) )
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return false;
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position += 4;
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if (memcmp (&header[position], "MXF\0", 4) )
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return false;
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return true;
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}
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