ppmtoy4m(1)

💖 ppmtoy4m(1) — the MJPEG tools manual, but make it a group chat 💖

okay bestie, sit down, hydrate, because we're about to talk about ppmtoy4m — she lives in the MJPEG tools manual and she is THAT girl. she takes your lil PPM pics and turns them into a YUV4MPEG2 stream. it's giving glow-up. it's giving pipeline icon. 🦋

✨ NAME ✨

ppmtoy4m — Convert PPM images to YUV4MPEG2 stream 💅

🌸 SYNOPSIS 🌸

ppmtoy4m [options] [ filename ]

🎀 DESCRIPTION 🎀

so like, ppmtoy4m converts one or more raw PPM images into a YUV4MPEG2 stream, all ready for further processing by other video tools. no cap. 🔥

output goes to stdout so you can pipe it straight into other MJPEG tools — yes queen, the pipeline is the moment. 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. and here's the tea: the input may contain multiple PPM images concatenated together, and ppmtoy4m will read and process them sequentially. all images must have identical size and format — no exceptions bestie, she does not do chaos. input images can be interpreted as whole progressive frames, interleaved fields, or (in pairs) as sequential fields. and the input images must have 8 bits per channel (i.e. maxval must be 255). that's the law. 📏

input images should be in the usual R'G'B' colorspace. they get converted to the Y'CbCr colorspace (ITU-R BT.601) — and chroma subsampled, if that's what you want — before output. slay. 💜

now this is the cute part: ppmtoy4m and y4mtoppm are inverses of each other. you can pipe the output of one into the other, and vice-versa. adorable. matching besties. 🫶 but ngl — the subsampling and colorspace operations are lossy in both directions, so don't come crying to me when the pixels aren't pixel-perfect. 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). iykyk. 😭

👑 OPTIONS 👑

ppmtoy4m accepts the following options, and yes, we're doing all of them:

• -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. (not me forgetting the channel order 🙈)
• -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. 👀 infinite loop energy, literally.
• -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

bestie listen. 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). don't say i didn't warn you. 💀

• -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 — yes, 15 whole frames of the same pic, she's committed:

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 — the pipeline is genuinely so satisfying:

ls *.tga | xargs -n1 tgatoppm | ppmtoy4m | yuvplay

ate. no crumbs. 🔥

🧚 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)

go read them. do it for her. 📚✨

and that's the whole page, bestie!! brought to you by the MJPEG Tools Team, dated 28 April 2004 — vintage, iconic, still slaying to this day. mwah. 💋🎀🦋