Am I too stupid or is there a bug in the codec?

T

ThomasS

Member
When I received my GH1 last thursday, I was very happy - this camery was litttle, neat and offered me all manual controls ever needed, plus an excellent image stabilizer in the stock lens.
But after shooting some test clips, disillusion came: Low light performance with the stock lens is pretty bad. As soon as you zoom over 14mm, f4 goodbye! On portrait focal lenghts 35-50mm you have at least f5 to f5.6, one stop less.
Cranking up the ISO to 1600 shows horrible color blotches and banding (see screen capture). The banding is on constant columns, so with small panning, it shows up even worse.
Even on smaller ISOs, e.g. skin tones become very unnatural (see http://vimeo.com/5035691, NOT due to vimeo recompression, already in the MTS file)

But the biggest problem is, the camera skips frames (see http://vimeo.com/5035635, starts at 5sec and then continues through the entire clip) and this is not a matter of the SDHC-card (I used a Sandisk Extreme III, class 6, rated 20MB/s read and write), as I shot about 100 clips with it, and a handful of the total show these effects.

Do I do something terribly wrong, is my copy of the camera defective or has this product a severe problem?

Thomas
 

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It is a PAL version, so I assumed, there's no pulldown removal necessary !? And it only shows up in 5 of about 100 files?
 
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i dont think that screen grabs all that bad for ISO 1600.
and for low light...go get your self a nice prime + adapter and shoot your
heart out. for what it is, and what it can do the kit lens is pretty cool.

weird that its dropping frames though. thats the first iv heard of it.
 
For interior shots you get yourself a nice lighting kit and light up the place for proper shooting. That is for pro work. Anything else get a video light and put it on top of the camera the good old fashion way. Skipping frames? Well there must be something going on with your cam as you are the first one to report the problem.
 
Are the frames skipped in your original footage? Or on vimeo? Vimeo converts everything to 24P, even if it's 30P so everything ends up getting skewered. If you upload the original MTS it might be easier to check if it's something software related. How are you importing your footage?
 
The frames are skipped in the original footage. Even when playing back on the camera display. And it's 25p, as it is the PAL version, so I'd expect constant frame dropping throughout the cilp. But the cliü - as well as the other corrupt ones - show this at random times with a random number of dropped frames (up to 5 I counted).
 
Why is it that the Phil Bloom material exhibits the least artifact issues?

I have his 1080P from Texas, then two other pieces he shot in 1080P converted to 720P, and they're better as in artifact/codec issue's then any of GH1 footage I have, seen.

Earlier I was on the Phone with Elton and we discussed this, and I was made aware of the 60i version of the GH1's may be inferior do do the encoding vs the Pal50i encoding.

Is this true?



.
 
well it's less data to encode. bloom doesn't do any crazy whip pans. However I've seen subject movement mud in his footage.
 
There is a lot of dry mud and nasty cactuses on Bloom's video. I saw that. There is a lot of heat from the sun hitting the dry mud and creating some strange dificult to describe cloud of something in about 6 seconds of the footage. The snake's skin also looks suspect as well as its movements were a little slow. The woman's hand holding the rope looked fake, like a prop. The font for the titles was adequate.
 
The original MTS file can be found here. BTW I looked at it in VLC player and it shows some really strange movement pattern.
The clip on vimeo in the original post was processed with FCP, a straight export to Quicktime.

Has anybody an idea, why we see these ugly color patterns in skin tones @ ISO200-400, like in my 2nd clip?
 
ThomasS said:
The original MTS file can be found here. BTW I looked at it in VLC player and it shows some really strange movement pattern.
...
Click to expand...

That´s really strange. I watched it with PP CS4, AE CS4 + Edius 5 - always the same. It skips several frames, varying in amount - instead it repeats frames. That´s unusable footage. Can someone of the other pal-users confirm this quirky behavior? What about the 720p50 footage? Same BS?
 
I've checked the m2ts and the file is OK, I mean it is not broken due to data corruption, the repeated frames have all macroblocks marked correctly.
 
You might have gotten a lemon. That footage doens't look right, definitely looks like skipped frames. I think there's about eight frames missing when it jumps.
 
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