.\" .TH "ppmtoy4m" "1" "28 April 2004" "MJPEG Linux Square" "MJPEG tools manual".SH "NAME"ppmtoy4m \- Convert PPM images to YUV4MPEG2 stream.SH "SYNOPSIS".B ppmtoy4m.RI [ options ].I [ filename ].SH "DESCRIPTION"\fBppmtoy4m\fP converts one or more raw PPM images into a YUV4MPEG2 streamready 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 optionalfilename.  The input may contain multiple PPM images concatenated together;\fBppmtoy4m\fP will read and process them sequentially.  All images must haveidentical size and format.  Input images can be interpreted as wholeprogressive 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 convertedto the Y'CbCr colorspace (ITU-R BT.601) (and chroma subsampled, if desired)before output.\fBppmtoy4m\fP and \fBy4mtoppm\fP are inverses of each other; you canpipe the output of one into the other, and vice-versa.  Note that thesubsampling and colorspace operations are lossy in both directions.  And,when converting to PPM, information on interlacing and sample aspect ratiois lost (but can be reconstructed by supplying command-line arguments to\fBppmtoy4m\fP)..SH "OPTIONS"\fBppmtoy4m\fP accepts the following options:.TP 5.BI \-o " num"Frame offset:  skip output of the first 'num' frames.  (default: 0).TP 5.BI \-n " num"Output a total of 'num' output frames.  Use '0' to specify all frames.(default: 0).TP 5.BI \-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.TP 5.BI \-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.TP 5.BI \-BInterpret data as being BGR rather than RGB..TP 5.BI \-I " x"Set interlacing mode, used to interpret the PPM image(s), and also encodedin output stream.  (default:  'p') p - progressive, non-interlaced t - top/upper-field-first interlaced b - bottom/lower-field-first interlaced.TP 5.BI \-LFor interlaced streams, treat each PPM image as two interleaved fields.(Otherwise, two PPM images will be read for each frame; one per field.).TP 5.BI \-r Repeat last input frame until output is complete.  If '-n 0' is also specified,last input frame will be repeated forever..TP 5.BI \-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 cositingThe subsampled modes use a lousy subsampling filter;better results will be achieved by passing the default 4:4:4 output toa scaler which supports subsampling, such as \fBy4mscaler\fP(1)..TP 5.BI \-v " [0,1,2]"Set verbosity level.   0 = warnings and errors only. 1 = add informative messages, too. 2 = add chatty debugging message, too..SH "EXAMPLES".hw ppmtoy4m yuvplay tgatoppmTo convert a file containing a single PPM file into a stream of 15(identical) frames:.RS 5ppmtoy4m -n 15 -r some-image.ppm.RETo convert a series of Targa format images (in the current directory)to a YUV4MPEG2 stream displayed by yuvplay:.RS 5ls *.tga | xargs -n1 tgatoppm | ppmtoy4m | yuvplay.RE.SH "AUTHOR"This man page was written by Matt Marjanovic..br If you have questions, remarks, problems or you just want to contactthe developers, the main mailing list for the MJPEG\-tools is:  \fImjpeg\-users@lists.sourceforge.net\fP.TP For more info, see our website at.I http://mjpeg.sourceforge.net/.SH "SEE ALSO".BR ppm (5),.BR y4mtoppm (1),.BR mjpegtools (1),.BR mpeg2enc (1),.BR y4mscaler (1),.BR yuv2lav (1),.BR yuvplay (1)