pixelated 7d footage

I've been shooting with my canon 7d for a few years. At the beginning i was content with shooting with everything standard but now i have done a lot more with a flat profile etc...recently though the quality of my footage has been rather terrible.

I can't quite work it out the reason, if it's:

a) my sensor is dirty and causing footage to pixelate, I sometimes shoot apertures up to f15/16 because it's so light and i shoot outdoors a lot and i want a large area in focus, mainly by the sea so when i change lenses salty air gets in etc...
b) maybe it's just sometimes the apertures although this problem happens now even at f2.8. I have bought a tiffen vari ND to try and make sure I can shoot at low apertures when outside. I still get these pixelated orginigal footage.

I have attached a shot of the 1080 30p footage that came off a recent clip that i noticed the pixelation real bad, you can see at the top of the shot how bad it is. `For an example of how bad it looks when the footage is part of an edit here is a vimeo clip that really shots off the quality being bad in the shots.
https://vimeo.com/4044​4725
https://vimeo.com/4044​4725

Please can someone enlighten me, it's runining all my shoots at the moment. I watch shots of philip blooms videos and he has landscape scenes with everything in perfect, no pixelation and then when i use f11 for a landscape everything is pielated...PLEASE can someone help...

jim__bob wrote in post #15169100
I have attached a shot of the 1080 30p footage that came off a recent clip that i noticed the pixelation real bad, you can see at the top of the shot how bad it is.

I haven't watched the clip, but looking at the screen grab I can see straight away what's probably causing the issue.

DSLR's shoot at a fairly low bit rate, and the frames are compressed to fit into this bit rate.

Now, with constant, high frequency shifting detail, such as the rippling waves with highlight glints, it will take most of the compression bandwidth to encode that stuff, and there isn't enough bandwidth left over for the more static background stuff - hence, you start to get compression artifacts.

There is an FXPHD video which demonstrates this really well.

The solution is to be able to increase the bit rate in the video recording - and most Canon DLR's cannot do this. However, you can do this is you run Magic Lantern on your 7D - Magic Lantern for the 7D is in development at the moment and is only in an alpha version (which doesn't yet have this feature) but it will be happening soon - so I strongly suggest investigating this when it is ready for prime time.

Increasing the video bit rate is only one of it's many many cool features.

thanks, i've seen some great sporting footage before with dslr's but maybe my problem is just there's too much movement going on. Tricky considering my thing is watersports footage haha!

Maybe it's time to buy that fs100 i keep looking to buy...

It seems like the footage becomes real noisy, as if my iso is way too high even though it's not. Is there any way around or just have to wait for magic lantern or go away from the DSLRs?

Is there any way a dirty mirror/sensor would effect the quality or is this all about data rates? Do you think it would be better to shoot in 720p so there's less data trying to be stored so even though it's a smaller shot there's less data going in so actually the picture will be better with no pixelation???

As a favor to you, I didn't mind watching that entire clip. That being said, I agree it is the bitrate limitation. The scenes with the most movement are most likely to hit the max bitrate limitation and be more pixellated.

jim__bob wrote in post #15169229
thanks, i've seen some great sporting footage before with dslr's but maybe my problem is just there's too much movement going on.

It's not really the movement as such, it's the high frequency, high-contrast detail. The compression algorithm targets this stuff first, and uses up the bandwidth to do it's best job of encoding that stuff, which is difficult to compress, so the remaining stuff has really poor detail.

jim__bob wrote in post #15169229
Is there any way around or just have to wait for magic lantern or go away from the DSLRs?

There is no way to increase the bitrate on the 7D other than use Magic Lantern.

jim__bob wrote in post #15169229
Is there any way a dirty mirror/sensor would effect the quality or is this all about data rates?

Nothing to do with the mirror or sensor. It's all about compression.

jim__bob wrote in post #15169229
Do you think it would be better to shoot in 720p so there's less data trying to be stored so even though it's a smaller shot there's less data going in so actually the picture will be better with no pixelation???

I don't know offhand as I don't have the various data to hand, or the differences shooting at a lower resolution, same frame rate has - you'd really need to do some tests with your material and understand how the camera encodes the scenes. It is of course highly scene-dependent. It makes sense that theoretically, 720 has less detail/resolution to encode, so *if* the data rate stays the same, then it's possible the picture encode is better (although the overall picture has less resolution). However, offhand, without investigating, I don't know if the data rate does stay the same at 720p, or if the camera uses a lower data rate to keep file sizes down.

Like I say, worth a test to understand the behaviour of the camera - this is why camera guys love doing camera tests so much...

(And you can start to see why getting Magic Lantern finally working on the 7D is so good...)