Linux Real Time MPEG Compression? 29
aszoth asks: "I working on a project that is going to require approximately 4 hours of video recording per day for about two months. We are currently using DVM tapes, however the extraction and compression time has left us with a large library of tapes un-converted. We are considering other methods, in particular real time MPEG 2 or MPEG 4 Compression. We also would like to be able to slow down our frame rate from the 29.7 fps to something along the lines of 5-15 fps. I am wondering if any one has any suggestions on possible ways to do such compression (or get similar results) with a Linux box. Thank you for any help you can give."
Ask Google. (Score:2, Insightful)
Re:Ask Google. (Score:4, Insightful)
Why is this person asking slashdot? For an answer. Google may be great but there's a lot of garbage out there. I'm sure the poster was hoping someone could help him out by sharing some personal experience.
It's a great compliment to the community that people can ask a question assuming there will be an informed, helpful response. The knee-jerk "google it" reaction that is so common these days is tearing apart this vital facet of the community.
this whole /. thing is about community, people. let's be helpful if we can. and remember, there's no such thing as a stupid question, just unhelpful answers.
Re:Ask Google. (Score:4, Informative)
Still, it is prudent to do your Google homework before posting to any online forum. This keeps the signal-to-noise ratio up and makes people feel it's worth to come back to the site later.
Actually, the knee-jerk RTFM/RTFGoogle answers you're witnessing are all about community! More specifically, about teaching people how to behave here at Ask Slashdot. Saying "search Google before posting to Ask Slashdot" is very much like saying "don't shout in the library".
--Bud
I need a clarification: (Score:2)
Re:I need a clarification: (Score:1)
You're gonna hate this... (Score:1)
Re:You're gonna hate this... (Score:1)
I believe mencoder has an option for this, or try possibly a webcam application of some kind (might end up with MJPEG, but that's more compressed than raw video).
Also, there is a port of VirtualDub to linux under way, though it wasn't usable last time I checked.
Mpeg4IP? (Score:5, Informative)
If you are not stuck with Linux, I would suggest using a mac - Quick Time Broadcaster does real time mpeg4 encoding at good quality even on old iBooks, and the mpeg-4 royalties are taken of as part of the cost of QuickTime Pro.
Re:Mpeg4IP? (Score:1)
hardware or software? (Score:4, Interesting)
These software packages can do mpeg2, maybe also mpeg4, though I'm not sure of that. They can do xvid and divx, if you're satisfied with that as mpeg4 alternative.
But if it's a lot of data, you need a lot of cpu power. It depends on the resolution and so...
A hardware encoder might suit you better then. Afaik there are only mpeg1 and mpeg2 encoders, even secondhand and cheap. I wonder if there are mpeg4 hardware encoders on the market.
Re:hardware or software? (Score:1)
MPEG (Score:4, Insightful)
What I'd like to know is if there are any standard formats that are good for cuts. DV is great, but takes up a lot of space (3 minutes on a CD). It'd be nice to archive easilly editable source, just at a lower-than-dv quality.
Re:MPEG (Score:2, Informative)
MJPEG (and hardware encoder/decoder) (Score:2)
Also, as a shameless plug, a friend of mine builds hardware MJPEG encoder/decoder boards for Linux. Check out http://www.linuxmedialabs.com/
Maybe this is what the original poster needed?
Paul B.
Re:MPEG (Score:1)
Hope that helps,
Ster
Other problems with MPEG (Score:2)
Another problem resulting from the interframe dependencies is that if there is too much time between frames (5-15 fps as opposed to the 25+ normally used with MPEG), then the algorithm won't be NEARLY as efficient, since it's tuned around a smaller time interval between frames. (Some other algorithms are tuned around 15ish, like many videoconferencing algorithms. OTOH, a videoconferencing algorithm designed to perform well at 30 FPS will often perform horribly at 15 FPS. This is the case with a codec I worked on at college - It had stunning quality at 30 FPS, but drop it to 15 and it started having serious issues.)
And the smartass answer is... (Score:4, Funny)
Re:And the smartass answer is... (Score:1)
Linux (none) 2.1.24-TiVo-2.5 #8 Wed May 8 15:38:27 PDT 2002 ppc unknown
Depends on the system power.... (Score:2, Informative)
If you have anything less than a dedicated 2GHz machine, you should seriously look into a hardware encoder.
Canopus makes some cheap mpeg encoder cards, but it looks like the Linux support is sparse...the WinTV PVR-250 [bit-tech.net] is fairly cheap ($150) and supports both MPEG1 & MPEG2 encoding.
So...why bother with something that *MIGHT* work and go with something that is certain to work...
In all fairness, some of the AV sync problems with ffmpeg are most likely due to a difference between the buffer sizes of the video and audio...
ffmpeg is your friend (Score:2)
Simple. (Score:2)
They will do realtime MJPEG encoding even on a relatively old machine. And because it is a hardware solution it should be less likely to jitter & choke every now and then.
AND because it is MJPEG and not MPEG like a previous post said it is good for re-editing later.
mpeg4ip (Score:1)