.\" .TH "y4mtoppm" "1" "28 April 2004" "MJPEG Linux Square" "MJPEG tools manual".SH "NAME"y4mtoppm \- Convert YUV4MPEG2 stream to PPM images.SH "SYNOPSIS".B y4mtoppm.RI [ options ].SH "DESCRIPTION"\fBy4mtoppm\fP converts a YUV4MPEG2 stream into a sequenceof 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).\fBy4mtoppm\fP will convert each pixel to the usual R'G'B' colorspace usedfor computer graphics.YUV4MPEG2 streams may (often!) have subsampled chroma planes.\fBy4mtoppm\fP can upsample "4:2:0 JPEG" streams using a simple, lousyalgorithm.  Better results will be obtained using a filters such as\fBy4mscaler\fP(1) which are capable of general-purpose subsamplingoperations.  \fBy4mtoppm\fP will fail on streams which have chromasubsampling modes other than 4:4:4 or 4:2:0-JPEG.For interlaced streams, these operations are performed on each fieldindividually.  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 afteranother.  If you want to turn such a "multi-image" PPM stream/file intoindividual files, use \fBpnmsplit\fP.  (Some PNM filters can processmulti-image files/streams; however, many written before June 2000 willonly process the first image.)\fBy4mtoppm\fP and \fBppmtoy4m\fP are inverses of each other; you canpipe the output of one into the other, and vice-versa.  Note that thecolorspace (and subsampling) 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"\fBy4mtoppm\fP accepts the following options:.TP 5.BI \-LFor interlaced streams, output a single PPM image for each frame, containingtwo interleaved fields.(Otherwise, two PPM images will be generated for each frame; one per field.).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 y4mtoppm pnmsplit lav2yuvTo turn the first 15 frames of an (MJPEG or DV) AVI file into individualPPM files:.RS 5lav2yuv -f 15 your-video.avi | y4mtoppm | pnmsplit - "your-video-%d.ppm".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 pnm (5),.BR ppmtoy4m (1),.BR mjpegtools (1),.BR mpeg2enc (1),.BR lav2yuv (1),.BR pnmsplit (1),.BR y4mscaler (1)