Provided by: mjpegtools_2.1.0+debian-6build1_amd64 bug

NAME

       y4mtopnm - Convert a YUV4MPEG2 stream to PNM images

SYNOPSIS

       y4mtopnm [options]

DESCRIPTION

       y4mtopnm  converts  a  YUV4MPEG2  stream  into  a sequence of raw PPM, PGM, or PAM images.
       (Technically, "pnm" comprises the PPM, PGM and PBM formats.  PAM is a fourth format, which
       can effectively contain any of the other three, and more.)

       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).   For  4:4:4  (color)  streams,
       y4mtopnm  will  convert  each  pixel  to  the  usual  R'G'B'  colorspace used for computer
       graphics, and produce PPM images.  "MONO" (luma-only) streams will be converted  to  full-
       range [0,255] grayscale and output as PGM images.

       YUV4MPEG2  streams  may  (often!)  have  subsampled  chroma  planes, but y4mtopnm will not
       process them (except in the special 'flatten' mode; see below).  Subsampled  streams  will
       need to be converted to 4:4:4 using a tool such as y4mscaler.

       If  y4mtopnm  is  given a "444ALPHA" stream (4:4:4 video with an 8-bit alpha channel), the
       results depend on whether or not the "-P" option is specified.  With "-P", it will produce
       PAM  images  with  a  TUPLTYPE of RGB_ALPHA, containing both color and alpha channel data.
       Without "-P", it will produce pairs of PPM and PGM images: a  PPM  for  the  color  pixels
       followed  by  a  PGM for the alpha channel data.  (Such a sequence of interspersed PPM and
       PGM images cannot be later re-processed by pnmtoy4m.  This feature is mostly for quick and
       easy stream debugging.)

       If multiple output images are generated, they are simply output one after another.  If you
       want to turn such a "multi-image" 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.)

       y4mtopnm and pnmtoy4m are inverses of each other; you can typically pipe the output of one
       into the other, and vice-versa (except for the "444ALPHA" case noted above and the "mixed-
       mode" case noted below).  Note that  the  colorspace  operations  can  be  lossy  in  both
       directions  (due  to range-compression and/or quantization).  And, when converting to PNM,
       information on interlacing and sample aspect ratio  of  a  stream  is  lost  (but  can  be
       reconstructed by supplying command-line arguments to pnmtoy4m).

OPTIONS

       y4mtopnm accepts the following options:

       -P   Produce  PAM  format output, instead of PPM and/or PGM.  PAM can encode a superset of
            PNM, but is not yet understood by as many graphics programs.   (Indeed,  surprisingly
            few of the NetPBM tools seem to understand it.)

       -D   Produce  a  separate output image for each field of each frame.  (Otherwise, a single
            image per frame, containing two interleaved fields, is created.)

            If the input stream is interlaced, the field-images are  output  in  temporal  order,
            i.e. the first image of a bottom-field-first stream will be the bottom-field.  If the
            stream is progressive or has "mixed-mode" interlacing, then  the  temporal  order  is
            ambiguous, and the top-field will always be output first.

            Note that it will not be possible to later use pnmtoy4m to reconstruct a "mixed-mode"
            stream from a sequence of PNM/PAM images.

       -f   Produce a special  'flattened'  output,  most  useful  for  analyzing  and  debugging
            streams.  All the planes of a frame/field are tiled together into an enlarged PGM (or
            grayscale PAM) output image as follows:
                           +-----+                    +-----+
                   4:4:4   |  Y  |    4:4:4 w/alpha   |  Y  |
                           +-----+                    +-----+
                           |  Cb |                    |  Cb |
                           +-----+                    +-----+
                           |  Cr |                    |  Cr |
                           +-----+                    +-----+
                                                      |  A  |
                           +-----+                    +-----+
                   4:2:2,  |  Y  |
                   4:2:0   +--+--+                    +-----+--+--+
                           |Cb|Cr|            4:1:1   |  Y  |Cb|Cr|
                           +--+--+                    +-----+--+--+
                                        +-----+
                                 MONO   |  Y  |
                                        +-----+
            In this mode,  any  YUV4MPEG2  chroma  format  is  accepted,  but  no  upsampling  or
            colorspace    conversion    is    performed.     This    is    essentially   just   a
            reformatting/permutation of the original data from the input stream into a PGM  image
            container.   All  the  other  command-line  flags continue to have the same effect on
            output.

       -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 | y4mscaler -O chromass=444  |  y4mtopnm  |  pnmsplit  -
            "your-video-%d.ppm"

AUTHOR

       This manual 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

       pam(5), pgm(5),  pnm(5),  ppm(5),  pnmtoy4m(1),  mjpegtools(1),  mpeg2enc(1),  lav2yuv(1),
       pnmsplit(1), y4mscaler(1)