/*****************************************************************************

 * mxpeg_helper.h: MXPEG helper functions

 *****************************************************************************

 * Copyright (C) 2012 VLC authors and VideoLAN

 *

 * 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 = vlc_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( vlc_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 (vlc_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;

}