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src/Source/LibTIFF4/tif_ojpeg.c  view on Meta::CPAN

   OJPEGReadHeaderInfoSecStreamSof.

   The restart interval and restart markers are the most tricky part... The restart
   interval can be specified in a tag. It can also be set inside the input JPEG stream.
   It can be used inside the input JPEG stream. If reading from strile data, we've
   consistenly discovered the need to insert restart markers in between the different
   striles, as is also probably the most likely interpretation of the original TIFF 6.0
   specification. With all this setting of interval, and actual use of markers that is not
   predictable at the time of valid JPEG header assembly, the restart thing may turn
   out the Achilles heel of this implementation. Fortunately, most OJPEG writer vendors
   succeed in reading back what they write, which may be the reason why we've been able
   to discover ways that seem to work.

   Some special provision is made for planarconfig separate OJPEG files. These seem
   to consistently contain header info, a SOS marker, a plane, SOS marker, plane, SOS,
   and plane. This may or may not be a valid JPEG configuration, we don't know and don't
   care. We want LibTiff to be able to access the planes individually, without huge
   buffering inside LibJpeg, anyway. So we compose headers to feed to LibJpeg, in this
   case, that allow us to pass a single plane such that LibJpeg sees a valid
   single-channel JPEG stream. Locating subsequent SOS markers, and thus subsequent
   planes, is done inside OJPEGReadSecondarySos.

   The benefit of the scheme is... that it works, basically. We know of no other that
   does. It works without checking software tag, or otherwise going about things in an
   OJPEG flavor specific manner. Instead, it is a single scheme, that covers the cases
   with and without JpegInterchangeFormat, with and without striles, with part of
   the header in JpegInterchangeFormat and remainder in first strile, etc. It is forgiving
   and robust, may likely work with OJPEG flavors we've not seen yet, and makes most out
   of the data.

   Another nice side-effect is that a complete JPEG single valid stream is build if
   planarconfig is not separate (vast majority). We may one day use that to build
   converters to JPEG, and/or to new-style JPEG compression inside TIFF.

   A dissadvantage is the lack of random access to the individual striles. This is the
   reason for much of the complicated restart-and-position stuff inside OJPEGPreDecode.
   Applications would do well accessing all striles in order, as this will result in
   a single sequential scan of the input stream, and no restarting of LibJpeg decoding
   session.
*/

#define WIN32_LEAN_AND_MEAN
#define VC_EXTRALEAN

#include "tiffiop.h"
#ifdef OJPEG_SUPPORT

/* Configuration defines here are:
 * JPEG_ENCAP_EXTERNAL: The normal way to call libjpeg, uses longjump. In some environments,
 * 	like eg LibTiffDelphi, this is not possible. For this reason, the actual calls to
 * 	libjpeg, with longjump stuff, are encapsulated in dedicated functions. When
 * 	JPEG_ENCAP_EXTERNAL is defined, these encapsulating functions are declared external
 * 	to this unit, and can be defined elsewhere to use stuff other then longjump.
 * 	The default mode, without JPEG_ENCAP_EXTERNAL, implements the call encapsulators
 * 	here, internally, with normal longjump.
 * SETJMP, LONGJMP, JMP_BUF: On some machines/environments a longjump equivalent is
 * 	conviniently available, but still it may be worthwhile to use _setjmp or sigsetjmp
 * 	in place of plain setjmp. These macros will make it easier. It is useless
 * 	to fiddle with these if you define JPEG_ENCAP_EXTERNAL.
 * OJPEG_BUFFER: Define the size of the desired buffer here. Should be small enough so as to guarantee
 * 	instant processing, optimal streaming and optimal use of processor cache, but also big
 * 	enough so as to not result in significant call overhead. It should be at least a few
 * 	bytes to accommodate some structures (this is verified in asserts), but it would not be
 * 	sensible to make it this small anyway, and it should be at most 64K since it is indexed
 * 	with uint16. We recommend 2K.
 * EGYPTIANWALK: You could also define EGYPTIANWALK here, but it is not used anywhere and has
 * 	absolutely no effect. That is why most people insist the EGYPTIANWALK is a bit silly.
 */

/* define LIBJPEG_ENCAP_EXTERNAL */
#define SETJMP(jbuf) setjmp(jbuf)
#define LONGJMP(jbuf,code) longjmp(jbuf,code)
#define JMP_BUF jmp_buf
#define OJPEG_BUFFER 2048
/* define EGYPTIANWALK */

#define JPEG_MARKER_SOF0 0xC0
#define JPEG_MARKER_SOF1 0xC1
#define JPEG_MARKER_SOF3 0xC3
#define JPEG_MARKER_DHT 0xC4
#define JPEG_MARKER_RST0 0XD0
#define JPEG_MARKER_SOI 0xD8
#define JPEG_MARKER_EOI 0xD9
#define JPEG_MARKER_SOS 0xDA
#define JPEG_MARKER_DQT 0xDB
#define JPEG_MARKER_DRI 0xDD
#define JPEG_MARKER_APP0 0xE0
#define JPEG_MARKER_COM 0xFE

#define FIELD_OJPEG_JPEGINTERCHANGEFORMAT (FIELD_CODEC+0)
#define FIELD_OJPEG_JPEGINTERCHANGEFORMATLENGTH (FIELD_CODEC+1)
#define FIELD_OJPEG_JPEGQTABLES (FIELD_CODEC+2)
#define FIELD_OJPEG_JPEGDCTABLES (FIELD_CODEC+3)
#define FIELD_OJPEG_JPEGACTABLES (FIELD_CODEC+4)
#define FIELD_OJPEG_JPEGPROC (FIELD_CODEC+5)
#define FIELD_OJPEG_JPEGRESTARTINTERVAL (FIELD_CODEC+6)

static const TIFFField ojpegFields[] = {
	{TIFFTAG_JPEGIFOFFSET,1,1,TIFF_LONG8,0,TIFF_SETGET_UINT64,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGINTERCHANGEFORMAT,TRUE,FALSE,"JpegInterchangeFormat",NULL},
	{TIFFTAG_JPEGIFBYTECOUNT,1,1,TIFF_LONG8,0,TIFF_SETGET_UINT64,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGINTERCHANGEFORMATLENGTH,TRUE,FALSE,"JpegInterchangeFormatLength",NULL},
	{TIFFTAG_JPEGQTABLES,TIFF_VARIABLE2,TIFF_VARIABLE2,TIFF_LONG8,0,TIFF_SETGET_C32_UINT64,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGQTABLES,FALSE,TRUE,"JpegQTables",NULL},
	{TIFFTAG_JPEGDCTABLES,TIFF_VARIABLE2,TIFF_VARIABLE2,TIFF_LONG8,0,TIFF_SETGET_C32_UINT64,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGDCTABLES,FALSE,TRUE,"JpegDcTables",NULL},
	{TIFFTAG_JPEGACTABLES,TIFF_VARIABLE2,TIFF_VARIABLE2,TIFF_LONG8,0,TIFF_SETGET_C32_UINT64,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGACTABLES,FALSE,TRUE,"JpegAcTables",NULL},
	{TIFFTAG_JPEGPROC,1,1,TIFF_SHORT,0,TIFF_SETGET_UINT16,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGPROC,FALSE,FALSE,"JpegProc",NULL},
	{TIFFTAG_JPEGRESTARTINTERVAL,1,1,TIFF_SHORT,0,TIFF_SETGET_UINT16,TIFF_SETGET_UNDEFINED,FIELD_OJPEG_JPEGRESTARTINTERVAL,FALSE,FALSE,"JpegRestartInterval",NULL},
};

#ifndef LIBJPEG_ENCAP_EXTERNAL
#include <setjmp.h>
#endif

/* We undefine FAR to avoid conflict with JPEG definition */

#ifdef FAR
#undef FAR
#endif

/*
  Libjpeg's jmorecfg.h defines INT16 and INT32, but only if XMD_H is
  not defined.  Unfortunately, the MinGW and Borland compilers include
  a typedef for INT32, which causes a conflict.  MSVC does not include