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Sourcecode: libv4l version File versions

pac207.c

/*

# PAC207 decoder
#               Bertrik.Sikken. Thomas Kaiser (C) 2005
#               Copyright (C) 2003 2004 2005 Michel Xhaard

# 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# Note this code was originally licensed under the GNU GPL instead of the
# GNU LGPL, its license has been changed with permission, see the permission
# mails at the end of this file.

*/

#include <string.h>
#include "libv4lconvert-priv.h"

#define CLIP(color) (unsigned char)(((color)>0xFF)?0xff:(((color)<0)?0:(color)))

/* FIXME not threadsafe */
static int decoder_initialized = 0;

static struct {
      unsigned char is_abs;
      unsigned char len;
      signed char val;
} table[256];

static void init_pixart_decoder(void)
{
    int i;
    int is_abs, val, len;
    for (i = 0; i < 256; i++) {
      is_abs = 0;
      val = 0;
      len = 0;
      if ((i & 0xC0) == 0) {
          /* code 00 */
          val = 0;
          len = 2;
      } else if ((i & 0xC0) == 0x40) {
          /* code 01 */
          val = -1;
          len = 2;
      } else if ((i & 0xC0) == 0x80) {
          /* code 10 */
          val = +1;
          len = 2;
      } else if ((i & 0xF0) == 0xC0) {
          /* code 1100 */
          val = -2;
          len = 4;
      } else if ((i & 0xF0) == 0xD0) {
          /* code 1101 */
          val = +2;
          len = 4;
      } else if ((i & 0xF8) == 0xE0) {
          /* code 11100 */
          val = -3;
          len = 5;
      } else if ((i & 0xF8) == 0xE8) {
          /* code 11101 */
          val = +3;
          len = 5;
      } else if ((i & 0xFC) == 0xF0) {
          /* code 111100 */
          val = -4;
          len = 6;
      } else if ((i & 0xFC) == 0xF4) {
          /* code 111101 */
          val = +4;
          len = 6;
      } else if ((i & 0xF8) == 0xF8) {
          /* code 11111xxxxxx */
          is_abs = 1;
          val = 0;
          len = 5;
      }
      table[i].is_abs = is_abs;
      table[i].val = val;
      table[i].len = len;
    }
    decoder_initialized = 1;
}

static inline unsigned char getByte(const unsigned char *inp,
                            unsigned int bitpos)
{
    const unsigned char *addr;
    addr = inp + (bitpos >> 3);
    return (addr[0] << (bitpos & 7)) | (addr[1] >> (8 - (bitpos & 7)));
}

static inline unsigned short getShort(const unsigned char *pt)
{
    return ((pt[0] << 8) | pt[1]);
}

static int
pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width,
    int step_size, int abs_bits)
{
    int col;
    int val;
    int bitpos;
    unsigned char code;

    if (!decoder_initialized)
      init_pixart_decoder();

    /* first two pixels are stored as raw 8-bit */
    *outp++ = inp[2];
    *outp++ = inp[3];
    bitpos = 32;

    /* main decoding loop */
    for (col = 2; col < width; col++) {
      /* get bitcode */

      code = getByte(inp, bitpos);
      bitpos += table[code].len;

      /* calculate pixel value */
      if (table[code].is_abs) {
          /* absolute value: get 6 more bits */
          code = getByte(inp, bitpos);
          bitpos += abs_bits;
          *outp++ = code & ~(0xff >> abs_bits);
      } else {
          /* relative to left pixel */
          val = outp[-2] + table[code].val * step_size;
          *outp++ = CLIP(val);
      }
    }

    /* return line length, rounded up to next 16-bit word */
    return 2 * ((bitpos + 15) / 16);
}

int v4lconvert_decode_pac207(struct v4lconvert_data *data,
  const unsigned char *inp, int src_size, unsigned char *outp,
  int width, int height)
{
/* we should received a whole frame with header and EOL marker
in myframe->data and return a GBRG pattern in frame->tmpbuffer
remove the header then copy line by line EOL is set with 0x0f 0xf0 marker
or 0x1e 0xe1 for compressed line*/
    const unsigned char *end = inp + src_size;
    unsigned short word;
    int row;

    /* iterate over all rows */
    for (row = 0; row < height; row++) {
      if ((inp + 2) > end) {
          V4LCONVERT_ERR("incomplete pac207 frame\n");
          return -1;
      }
      word = getShort(inp);
      switch (word) {
      case 0x0FF0:
          memcpy(outp, inp + 2, width);
          inp += (2 + width);
          break;
      case 0x1EE1:
          inp += pac_decompress_row(inp, outp, width, 5, 6);
          break;

      case 0x2DD2:
          inp += pac_decompress_row(inp, outp, width, 9, 5);
          break;

      case 0x3CC3:
          inp += pac_decompress_row(inp, outp, width, 17, 4);
          break;

      case 0x4BB4:
          /* skip or copy line? */
          memcpy(outp, outp - 2 * width, width);
          inp += 2;
          break;

      default: /* corrupt frame */
          V4LCONVERT_ERR("unknown pac207 row header: 0x%04x\n", (int)word);
          return -1;
      }
      outp += width;
    }

    return 0;
}




/*
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Date: Thu, 26 Jun 2008 01:17:37 +0200
From: Thomas Kaiser <thomas@kaiser-linux.li>
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To: Hans de Goede <j.w.r.degoede@hhs.nl>
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      mxhaard@magic.fr
Subject: Re: pac207 bayer decompression algorithm license question
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Hello Hans

Hans de Goede wrote:
> Hi,
>
> As you may have seen on the mailinglist, I've created a userspace
> library to handle cam specific format handling in userspace where it
> belongs, see:
> http://hansdegoede.livejournal.com/
Yes, I saw it on the mail list and I think it is a good idea :-)
>
> I would like to also add support for decompressing the pac207's
> compressed bayer to this lib (and remove it from the kernel driver)
> for this I need permission to relicense the decompress code under the
> LGPL (version 2 or later).
Actually, this was done by Bertrik Sikken (bertrik@zonnet.nl), Michel
Xhaard (mxhaard@magic.fr) and me. But Bertrik was the one who found out
how to decode the lines :-)
>
> Can you give me permission for this, or if the code is not yours put
> me in contact with someone who can?
For me it's no problem to release it with LGPL. Maybe you have to ask
the other one's also.
>
> Thanks & Regards,
>
> Hans

Rgeards, Thomas
*/

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From: Michel Xhaard <mxhaard@magic.fr>
To: Hans de Goede <j.w.r.degoede@hhs.nl>
Subject: Re: pac207 bayer decompression algorithm license question
Date: Thu, 26 Jun 2008 11:15:32 +0200
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Le jeudi 26 juin 2008 09:02, Hans de Goede a =E9crit=A0:
> Hi,
>
> As you may have seen on the mailinglist, I've created a userspace library
> to handle cam specific format handling in userspace, see:
> http://hansdegoede.livejournal.com/
>
> I would like to also add support for decompressing the pac207's compressed
> bayer to this lib (and remove it from the kernel driver) and I've heard
> from Thomas Kaiser that you are a co-author of the decompression code. In
> order to add support for decompressing pac207 compressed bayer to libv4l I
> need permission to relicense the decompression code under the LGPL (versi=
on
> 2 or later).
>
> Can you give me permission for this?
>
> Thanks & Regards,
>
> Hans
>
>
>
> p.s.
>
> Thomas has already given permission.

=46or me it is ok and a good idea for all free world familly ;-).
Bests regards
=2D-=20
Michel Xhaard
http://mxhaard.free.fr
*/

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Hallo Hans,

Hans de Goede wrote:
> Hi,
>
> As you may have seen on the mailinglist, I've created a userspace
> library to
> handle cam specific format handling in userspace, see:
> http://hansdegoede.livejournal.com/

O leuk, zoiets is naar mijn idee precies wat er nodig is voor webcam
support onder linux. Ik ben een jaar of 3 geleden heel actief geweest
met een aantal webcams, maar doe er tegenwoordig helemaal niets meer
aan.

> I would like to also add support for decompressing the pac207's compressed
> bayer to this lib (and remove it from the kernel driver) and I've heard
> from Thomas Kaiser that you are a co-author of the decompression code.
> In order to add support for decompressing pac207 compressed bayer to
> libv4l I need
> permission to relicense the decompression code under the LGPL (version 2
> or later).
>
> Can you give me permission for this?

Ja, vind ik goed.

Vriendelijke groet,
Bertrik
*/

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