y4mtoppm(1) MJPEG tools manual y4mtoppm(1) 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 re- sults will be obtained using a filters such as y4mscaler(1) which are capa- ble 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 indi- vidually. Fields can be output as separate PPM images in time-order (de- fault), or interleaved into full-frame images. If multiple PPM images are generated, they are simply output one after an- other. If you want to turn such a "multi-image" PPM stream/file into indi- vidual 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 sub- sampling) 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, con- taining 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) MJPEG Tools Team 28 April 2004 y4mtoppm(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | AUTHOR | SEE ALSO
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