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
   possible, 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
        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
         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

   -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
   bottom-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.
   However, 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)


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