NAME
ppmtoy4m - Convert PPM images to YUV4MPEG2 stream
SYNOPSIS
ppmtoy4m [options] [ filename ]
DESCRIPTION
ppmtoy4m converts one or more raw PPM images into a YUV4MPEG2 stream
ready 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 optional
filename. The input may contain multiple PPM images concatenated
together; ppmtoy4m will read and process them sequentially. All images
must have identical size and format. Input images can be interpreted
as whole progressive 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
converted to the Y’CbCr colorspace (ITU-R BT.601) (and chroma
subsampled, if desired) before output.
ppmtoy4m and y4mtoppm are inverses of each other; you can pipe the
output of one into the other, and vice-versa. Note that the
subsampling and colorspace 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
ppmtoy4m accepts the following options:
-o num
Frame offset: skip output of the first ’num’ frames. (default:
0)
-n num
Output a total of ’num’ output frames. Use ’0’ to specify all
frames. (default: 0)
-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
-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
-B Interpret data as being BGR rather than RGB.
-I x Set interlacing mode, used to interpret the PPM image(s), and also
encoded in output stream. (default: ’p’)
p - progressive, non-interlaced
t - top/upper-field-first interlaced
b - bottom/lower-field-first interlaced
-L For interlaced streams, treat each PPM image as two interleaved
fields. (Otherwise, two PPM images will be read for each frame;
one per field.)
-r Repeat last input frame until output is complete. If ’-n 0’ is
also specified, last input frame will be repeated forever.
-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 cositing
The subsampled modes use a lousy subsampling filter; better
results will be achieved by passing the default 4:4:4 output to a
scaler which supports subsampling, such as y4mscaler(1).
-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 convert a file containing a single PPM file into a stream of 15
(identical) frames:
ppmtoy4m -n 15 -r some-image.ppm
To convert a series of Targa format images (in the current directory)
to a YUV4MPEG2 stream displayed by yuvplay:
ls *.tga | xargs -n1 tgatoppm | ppmtoy4m | yuvplay
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), y4mtoppm(1), mjpegtools(1), mpeg2enc(1), y4mscaler(1),
yuv2lav(1), yuvplay(1)