View Full Version : MJPG ?s
06-04-2009, 11:28 AM
Sorry if these are simple questions or have been answered elsewhere. I tried searching and coundn't find them.
There are three advantages to AVCHD and one big negative vs. MJPG, as I see it:
- AVCHD is very hard to work with.
+ MJPG has a 2GB limit on file size.
+ Only AVCHD offers full HD resolution.
+ AVCHD takes about half the file space as MJPG.
The video work I am planning is destined for a non-Blueray DVD, so the lower resolution is not an issue. The file space issue is only a matter of money, and that will reduce over time. But the 2GB file size limit bothers me. So I have a couple (few?) questions:
At the end of 2GB will the camera keep shooting and just start FILE002 or will it stop?
If I merge the files later in editing will the break be visible?
If I stop a recording by pushing the video button can I push it again and start another 2GB file right away?
In general, what are the workarounds for the 2GB limit?
Thanks for any help.
06-04-2009, 12:02 PM
I had a look at the MJPEG clips Kholi posted to test to re-time to 24fps just now and found a nice surprise.
It isn't Motion JPEG, it's Photo JPEG, a more efficient version, typically have only 40% of MJPEGs file size for same image quality. The two clips Kholi posted look really nice and it's a shame this option only do 30fps as it took my MacPro 4 core 2.66GHz machine 10 minutes in Compressor to re-time Kholis 20 sec clip to 24fps. I'd venture that single smartest thing Panasonic could do with GH1 is add 24 and 25fps to the MJPEG (PJPEG?!) encoding. Not sure it has the processor power to do 1080 30/25/24 but that would be simply awesome. I work in PJPEG 75% quality all the time through my Blackmagic Design Decklink HD card for SD broadcast.
Good info about the codec here from Marco Solario - click on 4:2:2 C in the small menu bar and scroll all the way down:
Apologies if this has been reported before.
As for your questions I don't know as I don't have the camera yet.
06-04-2009, 01:40 PM
Interesting. In the GH1 manual they list the spec as "QuickTime Motion JPEG". It still takes more bits than AVCHD.
For a 16GB card (again per the manual):
MJPEG HD (1280x720 30fps) 1 hour 7 min.
AVCHD SH (1280x720 60fps) 2 hours
So AVCHD is still a more compressed format, by about 2:1.
I'd still rather use MJPEG if I can work around the 2GB limit.
06-05-2009, 09:20 AM
Does anyone with a GH1 already know the answer to these questions.?
Thanks for any help on this.
06-05-2009, 03:52 PM
Let me let my camera run in MJPEG and see what happens.
06-05-2009, 04:00 PM
Super, thanks. I was afraid this was one of those "everyone should already know the answer" type of questions.
06-05-2009, 04:02 PM
It's running now. If I had to hazard a guess I'd say it limits the length of your shot rather than just creating a new file and continuing to roll. I only say that because it's giving me a time remaining time of about 8:30 and it's an empty 16Gb card. It should be able to record for a couple hours. Anyway, we'll know in 7 minutes.
06-05-2009, 04:09 PM
I'm holding my breath.....
Actually I suspected the same thing. If it was going to just keep going I would guess they would have mentioned it in the manual. I wonder why it is limited. I doubt it is similar to the EU limitation on avoiding taxes. It could be a spec, but it would seem they could just ignore that. Maybe QuickTime (Apple) won't let it go past 2GB. Or maybe Panasonic is trying to boost AVCHD. All kind of possibilities.
06-05-2009, 04:15 PM
I wasn't watching it intently but it seems to have stopped with a file size of 1.87 Gb. When I turned the camera back on from powersave mode it was ready to record against with a time remaining of 8:20. So I'd assume it just stops at it's filesize limit and needs to be started again.
06-05-2009, 04:22 PM
Could you try starting a record and then stop it and then start another right away to see if the counter starts over at 8:20? I suspect that is what will happen, but want to be sure.
06-05-2009, 04:26 PM
Oddly enough, I started it again and I'm at 9:20 recorded with 4:47 remaining. Probably because I'm not moving the camera and it's expecting to have to do more compression.
When it stops recording I'll press it again to see if it just starts back up.
The time remaining meter is obviously just an estimate, it's moving slower than the time recorded meter.
06-05-2009, 04:41 PM
I got to around 20:22.00 before it stopped, again at a file size of 1.87 GB. I was able to restart recording within a second basically. As soon as I recognized that it had stopped I pushed the record button again and it started a new file with a new time remaining counter of 8:20. So obviously the time remaining counter will vary depending on the nature of your footage. But I suppose if it's something that doesn't require a lot of compression then it'll just run longer. The upside is that the time remaining counter, while not accurate in terms of real-world time, does correspond directly with the end of the recording limit. What I mean is that it might not be really 8:20 remaining, but when it's approaching zero, it really is about to stop, just at a different rate than it's saying.
06-05-2009, 05:23 PM
Fantastic! Thanks for all the answers. Now if I could just find a way to buy one before my vacation next Friday I would be really happy. Nothing but frustration. I'm coming from a 4x5 background and I thought a high-end dealer here in Colorado was the way to go to get one. I was very wrong.
This answers all my questions. I'll wait until tomorrow and then I'll close this thread.
Thanks again to Martti too.
06-05-2009, 05:26 PM
No problem. I know how tough it is to make a decision without being able to know all the facts.
06-09-2009, 03:56 AM
Is the 2GB lenght limit imposed on all GH1 versions or on the European models only.
Anyhow, 2GB is 8:30 minutes of recording, which is a lot. Watch on closely at any TV or movie and you can easily discover that professional recording is no more than few second for every scene. Prolonged,continous shots are very boring.
06-09-2009, 06:34 AM
The MJPG 2GB limit is true for all models. The European restriction is anything that records 30min or longer, MJPG or AVCHD or anything else, must pay a much higher tax. So Panasonic has decided to limit recordings to 29:59 in Europe.