y4mtopnm(1)
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)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
