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)