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 the mpeg2enc(1) MPEG encoder and image processing filters like yuvscaler(1). 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 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

-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: 420_jpeg)
      420_jpeg - 4:2:0 JPEG/MPEG-1, interstitial cositing
     420_mpeg2 - 4:2:0 MPEG-2, horizontal cositing Changing the subsampling mode from the default won't necessarily make anything better. This option is just for experimenting.

-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), yuvscaler(1), yuv2lav(1), yuvplay(1)