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ppmtoy4m(1)


NAME

   ppmtoy4m - Convert PPM images to YUV4MPEG2 stream

SYNOPSIS

   ppmtoy4m [options] [ filename ]

DESCRIPTION

   ppmtoy4m  converts  one  or more raw PPM images into a YUV4MPEG2 stream
   ready for further processing by other video tools.

   Output is to stdout to facilitate piping to  other  MJPEG  tools.   The
   size of the output frame(s) is determined from the (first) input image.

   Input is a 'raw' format PPM image, read from stdin or from the optional
   filename.  The input  may  contain  multiple  PPM  images  concatenated
   together; ppmtoy4m will read and process them sequentially.  All images
   must have identical size and format.  Input images can  be  interpreted
   as  whole  progressive  frames,  interleaved  fields,  or (in pairs) as
   sequential fields.  The input images must have 8 bits per channel (i.e.
   'maxval' must be 255).

   Input  images  should  be  in  the  usual  R'G'B' colorspace.  They are
   converted  to  the  Y'CbCr  colorspace  (ITU-R  BT.601)   (and   chroma
   subsampled, if desired) before output.

   ppmtoy4m  and  y4mtoppm  are  inverses  of each other; you can pipe the
   output  of  one  into  the  other,  and  vice-versa.   Note  that   the
   subsampling  and  colorspace  operations  are lossy in both directions.
   And, when converting to PPM,  information  on  interlacing  and  sample
   aspect  ratio  is  lost (but can be reconstructed by supplying command-
   line arguments to ppmtoy4m).

OPTIONS

   ppmtoy4m accepts the following options:

   -o num
        Frame offset:  skip output of the first 'num'  frames.   (default:
        0)

   -n num
        Output  a  total  of  'num' output frames.  Use '0' to specify all
        frames.  (default: 0)

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

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

   -B   Interpret data as being BGR rather than RGB.

   -I x Set interlacing mode, used to interpret the PPM image(s), and also
        encoded in output stream.  (default:  'p')
         p - progressive, non-interlaced
         t - top/upper-field-first interlaced
         b - bottom/lower-field-first interlaced

   -L   For  interlaced  streams,  treat each PPM image as two interleaved
        fields.  (Otherwise, two PPM images will be read for  each  frame;
        one per field.)

   -r   Repeat  last  input  frame until output is complete.  If '-n 0' is
        also specified, last input frame will be repeated forever.

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

        The 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.
         2 = add chatty debugging message, too.

EXAMPLES

   To convert a file containing a single PPM file  into  a  stream  of  15
   (identical) frames:

        ppmtoy4m -n 15 -r some-image.ppm

   To  convert  a series of Targa format images (in the current directory)
   to a YUV4MPEG2 stream displayed by yuvplay:

        ls *.tga | xargs -n1 tgatoppm | ppmtoy4m | yuvplay

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

   ppm(5),    y4mtoppm(1),   mjpegtools(1),   mpeg2enc(1),   y4mscaler(1),
   yuv2lav(1), yuvplay(1)



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