/**********************************************************************/
/*                                                                    */
/* documentation to create mpeg files from AVS                        */
/*                                                                    */
/* 15 dec 1993                                                        */
/* P. Fulconis (CICG computer center of grenoble university (France)) */
/*                                                                    */
/**********************************************************************/


Introduction
------------

``image to YUV'' module writes AVS images (created by Geometry Viewer, for example) in yuv format.

``image to PPM'' module writes AVS images in ppm format.


Both formats can be read by mpeg encoder.

A ppm image will have a memory size twice bigger than the yuv one, but it can
be visualised by xv.

Both modules also create the parameter file for the mpeg encoder.


example of network :

       geometry viewer
             |
             |
        Image to YUV



compilation of the modules :
--------------------------

to compile write_ppm and write_yuv :  

    after have modified the makefile (HOME, WRITE),

      make  or  make all  (compilation of the 2 modules)
 or   make write_ppm
 or   make write_yuv



"image to YUV" and "image to PPM" modules :
-----------------------------------------

- File name    : name of image files created
                 The number of current image and the .yuv (or .ppm) extension
                 is added by the system. (ex: image3.yuv)
                 these files are written in the directory $HOME/AVS/Images,
                 if this directory exists, or in the current directory.


- img number   : number of the current image (not written yet)

- reset        : reset of the image number
                 (this number is also reseted when file name changed)

- on           : on/off switch

- on_next      : switch 'on' at the next time
                 the current image is not written
                 this is usefull when we want to read a sequence of images
                 using Animator
                 (the first image written will be the first displayed)

- param        : create the parameter file for mpeg encoder <file name>.param
                 this file is written in the directory $HOME/AVS/mpeg, if this
                 directory exists, or in the current directory.


- mpeg_encode  : creation of the mpeg file

- mpeg_play    : play the mpeg file



Creation of the mpeg file (without AVS):
-------------------------

When yuv (or ppm) images, and the parameter file (<file name>.param),
 are created, execute   mpeg_encode <parameter file name>

The image file <file name>.mpg will be created


To read (play) mpeg file :  mpeg_play <mpeg file name>


Sources for public domain files not included here
-------------------------------------------------

1) get mpeg_encode via anon ftp:
toe.berkeley.edu:/pub/multimedia/mpeg/{README-mpeg_encode,mpeg_encode-1.2.tar.Z}
Name:    toe.CS.Berkeley.EDU
Address:  128.32.149.117
Aliases:  toe.berkeley.edu

2) get mpeg_play via anon ftp:
toe.berkeley.edu:/pub/multimedia/mpeg/{README-mpeg_play,mpeg_play-2.0.tar.Z}
Name:    toe.CS.Berkeley.EDU
Address:  128.32.149.117
Aliases:  toe.berkeley.edu

3) you can get the following files via anonymous ftp as well,
   in case you're not using an IBM RS/6000 platform, in which
   case they're already here for you

-rwxrwxr-x  1 avs      14852 Nov 23  1992 arg.h*
-rwxrwxr-x  1 avs      11534 Nov 23  1992 bin.h*
-rwxrwxr-x  1 avs      29938 Nov 23  1992 im.h*
-rwxrwxr-x  1 avs    1047665 Nov 23  1992 libim.a*
-rwxrwxr-x  1 avs      86592 Nov 23  1992 libsdsc.a*
-rwxrwxr-x  1 avs       5295 Nov 23  1992 sdsc.h*
-rwxrwxr-x  1 avs      14798 Nov 23  1992 sdscconfig.h*
-rwxrwxr-x  1 avs       8231 Nov 23  1992 tag.h*

ftp.sdsc.edu:/pub/sdsc/graphics/imtools/<PLATFORM> 
		(there are a bunch of diferent platforms supported)
Name:    rosebud.sdsc.edu
Address:  198.17.47.33
Aliases:  ftp.sdsc.edu

There's a couple of files out there under 

	/pub/sdsc/graphics/imtools/<PLATFORM> 

(there are a bunch of diferent platforms supported).  You will need to 
grab imtools_v2.1.tar.Z and libsdsc_v2.1.tar.Z, uncompress and untar them,
and you will find the .h and other files in there.

4) create libppmyuv.a from the mpeg_encode-1.2.tar.Z file you downloaded in 
   step 1) above.

Insert in the Makefile of mpeg_encode-1.2/misc the lines:

lib: ppmtoyuv
        ar ruvl libppyuv.a $(O)/ppmtoyuv

You have to add in the original ppmtoyuv.c file
(from mpeg_encode-1.2/misc) this function :


extern int  ppm2yuv (FILE *fin, FILE *fout, int *h, int *w) ;

int  ppm2yuv (FILE *fin, FILE *fout, int *h, int *w)
{
    if ( ! ReadPPM(fin) )
    {
        fprintf(stderr, "Error reading PPM input file!!!\n");

        return(-1);
    }

    PPMtoYUV();

    WriteYUV(fout);


    *h = height;
    *w = width;

}


Just for info, here is the main function (which is very similar) :

void    main(int argc, char **argv)
{
    if ( ! ReadPPM(stdin) )
    {
        fprintf(stderr, "Error reading PPM input file!!!\n");
        exit(1);
    }

    PPMtoYUV();

    WriteYUV(stdout);
}


And, of course,  now you need to execute 'make lib'.