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y4mcolorbars(1)               MJPEG tools manual               y4mcolorbars(1)


NAME

       y4mcolorbars - Create a YUV4MPEG2 stream containing a colorbar test
       pattern


SYNOPSIS

       y4mcolorbars [options]


DESCRIPTION

       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
       possible, given the constraints of the Y'CbCr colorspace.

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


OPTIONS

       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
            integer 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
            pattern:
             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
            output 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.


EXAMPLES

       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
       bottom-field-first interlaced 4:3 PAL source:

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


BUGS

       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.
       However, the difference is within 1-bit of Y' accuracy anyway.


AUTHOR

       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:
         mjpeg-users@lists.sourceforge.net

       For more info, see our website at
              http://mjpeg.sourceforge.net


SEE ALSO

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

MJPEG Tools Team                 28 April 2004                 y4mcolorbars(1)

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