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+			----------------
+			| FILE FORMATS |
+			----------------
+
+PPM FORMAT
+----------
+
+See http://netpbm.sourceforge.net/doc/ppm.html .
+
+
+UCB YUV FORMAT
+--------------
+
+You should be aware that the YUV format used in the MPEG encoder is DIFFERENT
+than the Abekas YUV format.  The reason for this is that in MPEG, the U and
+V components are subsampled 4:1.
+
+To give you an idea of what format the YUV file must be in, the following
+code will read in a YUV file:
+
+    unsigned char **y_data, **cr_data, **cb_data;
+
+    void	ReadYUV(char *fileName, int width, int height)
+    {
+	FILE *fpointer;
+	register int y;
+
+	/* should allocate memory for y_data, cr_data, cb_data here */
+
+	fpointer = fopen(fileName, "r");
+
+	for (y = 0; y < height; y++)			/* Y */
+	    fread(y_data[y], 1, width, fpointer);
+
+	for (y = 0; y < height / 2; y++)			/* U */
+	    fread(cb_data[y], 1, width / 2, fpointer);
+
+	for (y = 0; y < height / 2; y++)			/* V */
+	    fread(cr_data[y], 1, width / 2, fpointer);
+
+	fclose(fpointer);
+    }
+
+There are two reasons why you'd want to use YUV files rather than PPM files:
+	1)  The YUV files are 50% the size of the corresponding PPM files
+	2)  The ENCODER will run slightly faster, since it doesn't have to
+	    do the RGB to YUV conversion itself.
+
+
+ABEKAS YUV FORMAT 
+-----------------
+
+The Abekas YUV Format interlaces the Y, U, and V values in a 4:2:2 format.
+The interlacing pattern is
+
+UYVY
+
+for each group of 4 bytes in the file.
+
+
+PHILLIPS YUV FORMAT 
+-------------------
+
+The Phillips YUV Format interlaces the Y, U, and V values in a 4:2:2 format.
+The interlacing pattern is
+
+YVYU
+
+for each group of 4 bytes in the file.
+
+
+You may specify either ABEKAS, PHILLIPS, or UCB as the YUV_FORMAT when
+encoding ; the encoder defaults to UCB YUV_FORMAT if not specified.
+In addition, if you've got a weird interlacing format, you can also
+try and de-interlace it by giving the YUV pattern in the YUV_FORMAT.
+So a YUV 4:4:4 format would be
+
+YUVYUV
+