NAME

       y4mtoppm - Convert YUV4MPEG2 stream to PPM images

SYNOPSIS

       y4mtoppm [options]

DESCRIPTION

       y4mtoppm converts a YUV4MPEG2 stream into a sequence of raw PPM images.

       Output is to stdout (but feel free to have the shell redirect to a file).

       Input  is  read from stdin, like all other YUV4MPEG2 filters and tools.  YUV4MPEG2 streams
       contain frames using the Y'CbCr colorspace (ITU-R BT.601).   y4mtoppm  will  convert  each
       pixel to the usual R'G'B' colorspace used for computer graphics.

       YUV4MPEG2  streams  may  (often!)  have  subsampled  chroma planes.  y4mtoppm can upsample
       "4:2:0 JPEG" streams using a simple, lousy algorithm.  Better  results  will  be  obtained
       using  a  filters  such  as  y4mscaler(1) which are capable of general-purpose subsampling
       operations.  y4mtoppm will fail on streams which have chroma subsampling modes other  than
       4:4:4 or 4:2:0-JPEG.

       For interlaced streams, these operations are performed on each field individually.  Fields
       can be output as separate PPM images in time-order (default), or  interleaved  into  full-
       frame images.

       If  multiple  PPM  images are generated, they are simply output one after another.  If you
       want to turn such a "multi-image" PPM stream/file into  individual  files,  use  pnmsplit.
       (Some PNM filters can process multi-image files/streams; however, many written before June
       2000 will only process the first image.)

       y4mtoppm and ppmtoy4m are inverses of each other; you can pipe the output of one into  the
       other, and vice-versa.  Note that the colorspace (and subsampling) 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

       y4mtoppm accepts the following options:

       -L   For interlaced streams, output a single PPM image  for  each  frame,  containing  two
            interleaved fields.  (Otherwise, two PPM images will be generated for each frame; one
            per field.)

       -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 turn the first 15 frames of an (MJPEG or DV) AVI file into individual PPM files:

            lav2yuv -f 15 your-video.avi | y4mtoppm | pnmsplit - "your-video-%d.ppm"

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),   pnm(5),   ppmtoy4m(1),   mjpegtools(1),  mpeg2enc(1),  lav2yuv(1),  pnmsplit(1),
       y4mscaler(1)