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y4mcolorbars(1)		      MJPEG tools manual	       y4mcolorbars(1)

       y4mcolorbars  -	Create	a  YUV4MPEG2 stream containing a colorbar test

       y4mcolorbars [options]

       y4mcolorbars creates a YUV4MPEG2	stream consisting entirely  of	frames
       containing  a colorbar test pattern.  The pattern attempts to reproduce
       the standard SMPTE EG-1-1990 colorbar test signal as faithfully as pos-
       sible, given the	constraints of the Y'CbCr colorspace.

       Output is to stdout to facilitate piping	to other MJPEG tools.

       y4mcolorbars accepts the	following options:

       -n num
	    Output a total of 'num' output frames. [default: 1]

       -F n:d
	    Set	framerate encoded in output stream, as an exact	integer	ratio.
	    Common rates are:
	     24000:1001	- NTSC 3:2 pulldown converted film
		   24:1	- native film
		   25:1	- PAL/SECAM
	     30000:1001	- NTSC video [default]
		   50:1	- PAL field rate
	     60000:1001	- NTSC field rate

       -W w Set	frame width. [default: 720]

       -H h Set	frame height. [default:	480]

       -A n:d
	    Set	pixel aspect ratio encoded in output stream, as	an exact inte-
	    ger	ratio.	Common ratios are:
		 1:1  -	square pixels (e.g. computer graphics)
		10:11 -	CCIR-601 NTSC [default]
		59:54 -	CCIR-601 PAL

       -I x Set	interlacing mode, used to interpret the	PPM image(s), and also
	    encoded in output stream.
	     p - progressive, non-interlaced [default]
	     t - top/upper-field-first interlaced
	     b - bottom/lower-field-first interlaced

       -Q n Data to place in the "-I/+Q" patches in the	bottom row of the pat-
	     0 -  -I and +Q at 20% (20IRE)  [default]
	     1 -  -I and +Q at 50% (50IRE)
	     2 -  +Cb and +Cr at 100%

       -S mode
	    Set	chroma subsampling mode.
		   444 - 4:4:4 (no subsampling)	[default]
	       420jpeg - 4:2:0 JPEG/MPEG-1, interstitial cositing
	      420mpeg2 - 4:2:0 MPEG-2, horizontal cositing

	    The	 supported  subsampled	modes  use a lousy subsampling filter;
	    better results will	be achieved by passing the default 4:4:4  out-
	    put	to a scaler which supports subsampling,	such as	y4mscaler(1).

       -v [0,1,2]
	    Set	verbosity level.
	     0 -  warnings and errors only.
	     1 -  add informative messages, too. [default]
	     2 -  add chatty debugging message,	too.

       To  create  and display 200 frames of colorbars corresponding to	a top-
       field-first interlaced 4:3 NTSC source:

	    y4mcolorbars -n 200	-It -S 420jpeg | yuvplay

       To create and display 200 frames	of colorbars corresponding to  a  bot-
       tom-field-first interlaced 4:3 PAL source:

	    y4mcolorbars -n 200	-H 576 -F 25:1 -A 59:54	-Ib | yuvplay

       First,  it's not	clear to the author (who hasn't	actually ever seen the
       SMPTE EG-1-1990 document	itself)	what the absolute excursion of the  -I
       and  +Q	regions	 is supposed to	be; however, the phase is correct, and
       that should be the critical feature.  Second, the PLUGE bars, of	-4 and
       +4  IRE,	 can  never  be	precisely synthesized --- the Y' digital space
       maps [16,235] over the full luma	excursion, but the full	luma excursion
       in  analog  space depends on whether or not 7.5 IRE NTSC	setup is being
       used by whatever	device eventually produces the	analog	output.	  How-
       ever, the difference is within 1-bit of Y' accuracy anyway.

       This man	page was written by Matt Marjanovic.
       If  you	have  questions, remarks, problems or you just want to contact
       the developers, the main	mailing	list for the MJPEG-tools is:

       For more	info, see our website at

       mjpegtools(1), mpeg2enc(1), y4mscaler(1), yuv2lav(1), yuvplay(1)

MJPEG Tools Team		 28 April 2004		       y4mcolorbars(1)


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