Re: [Mjpeg-users] Libquicktime Make Error

[Steven M. S. <sm...@2B...>]

On Sat, 10 Jan 2004 ra...@ih... wrote:

> I have checked the List Archive and apart from a Patch to Libquicktime in 2002

> I am installing libquicktime-0.9.2 with jpeg-mmx-0.1.4 and 
> mjpegtools-1.6.1.92.libmjpeg
> I have looked at libmjpeg.h lines 44, etc and libmjpeg.c, lines 96 etc, but am 
> In file included from libmjpeg.c:25:
> libmjpeg.h:44: error: parse error before "jmp_buf"
> libmjpeg.h:44: warning: no semicolon at end of struct or union
> libmjpeg.h:70: error: field `jpeg_error' has incomplete type
> libmjpeg.c: In function `mjpeg_error_exit':
> libmjpeg.c:96: warning: implicit declaration of function `longjmp'
> libmjpeg.c:96: error: dereferencing pointer to incomplete type
> libmjpeg.c: In function `append_buffer':
> libmjpeg.c:325: warning: implicit declaration of function `memcpy'
> libmjpeg.c: In function `decompress_field':
> libmjpeg.c:586: warning: implicit declaration of function `setjmp'
> libmjpeg.c: In function `find_marker':
> libmjpeg.c:1338: warning: comparison between signed and unsigned
> libmjpeg.c: In function `table_offsets':
> libmjpeg.c:1392: warning: implicit declaration of function `bzero'
> make[3]: *** [libmjpeg.lo] Error 1
> make[3]: Leaving directory 

	It took a little while to realize that the errors were from
	building libquicktime instead of mjpegtools - time for another
	cup of coffee ;)

	The problem I suspect is the version of the PNG library installed
	on your system.   What version of libpng do you have?

	libquicktime is (incorrectly I believe) using <png.h> to obtain
	the definition of 'jmp_buf'.  If you look at line 34 in libmjpeg.h
	you will see:

	#include <png.h>       /* Need setjmp.h included by png.h */

	If a program needs <setjmp.h> it should include it explicitly rather
	than relying on another unrelated header file.   libmjpeg.h should
	have done a '#include <setjmp.h>' rather than assuming that <png.h>
	would do it.

	It seems that later versions of libpng do include <setjmp.h> and
	the libquicktime folks rely on that behaviour.   I'd report that
	as a bug in libquicktime.

	In the meantime you can work around this in two ways:

	1) Add a '#include <setjmp.h>' to libmjpeg.h

	or 

	2) Install a newer version of libpng that has the libquicktime 
	   desired behaviour.

	The other warning errors (about bzero, etc) I think are due to not
	including <string.h>.    It's possible that libquicktime is relying
	on <png.h> to also do the include of string.    You can add a
	'#include <string.h>' and see if that causes the other warning errors
	to go away.

	Good Luck!

	Cheers,
	Steven Schultz