Magic Lantern AJ 5.6 test thread 80Mbit/s stable!

squig

squig

Veteran
I've been running a series of tests on the new manually adjustable CBR (constant bit rate) encoder that has been added to the AJ 5.6 build and all I can say is :2vrolijk_08::love4::beer::dankk2::thumbsup:

I've run some CBR torture tests and can report that the codec is stable running at the 160% setting @ 73Mbit/s average, peaking at 79Mbit/s. Test conditions- harsh sunlight, foliage, grass, brick walls, 17mm lens @ infinity, whip pans, sound recording on, 160 ISO, 24p, 1/50 shutter, cinestyle, and a Sandisk extreme 8Gb 60Mb/s card. I can't think of a tougher test for a codec and it was totally stable at 160%. At 170% it stopped recording as soon as I tried to whip pan with the codec peaking at 82Mbit/s. My earlier testing of the VBR suggests that 80Mbit/s is about the limit for the buffer/sandisk extreme card. There are some newer faster cards on the market now so it may be possible to break the 80Mbit/s barrier.

I also ran some tests indoors at night under CFLs The codec is maxing out at 68Mbit/s even at 400%? It's doing 59Mbit/s at 150% and 68Mbit/s at 160%. It has been totally stable at this bit-rate. On a slower 30Mb/s card it was unstable above 150% (59Mbit/s). I was shooting with a 50mm lens @ f/1.2 1250 ISO with cinestyle loaded. I've been doing a grade and comparing the footage to the standard CBR setting and I can't see any real improvement in the compression but these weren't stressful conditions for the codec and I don't have a high end monitoring setup for critical evaluation. I haven't had a chance to compare the standard bit-rate to the 80Mbit/s outdoor footage, I think I'll leave that that to somebody with nicer toys.

You can download the AJ 5.6 build here http://groups.google.com/group/ml-devel/browse_thread/thread/e808262c0e02a31f/7460a4178b491c5a

It only runs on the Canon 2.0.4 firmware, there is a link to the 2.0.4 firmware on the same page. As always be aware this is beta firmware, I haven't had any crashes yet. There's a bunch of other enhancement like cropmarks selectable from the menu and false colour. I haven't tested it personally yet but I think external monitoring is up and running now too.

Normally when there's a 5D breakthrough I go out and shoot a film of the kids but I'm flat out doing pre-production on my feature and one of the kids has chickenpox. :violin:

Please report any bugs to the ML team and post about them here too.

Great work and many thanks to the Magic Lantern dev guys!
 
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The manual CBR settings are adjustable in the Magic Lantern menu by a percentage value. 100% being the standard Canon firmware bit-rate (around 46Mbit/s)
 
There is also a VBR (variable) setting but I tested it when it was first implemented into ML and couldn't get it to operate reliably even with the fastest available CF cards. I asked the developer if it was possible to push the CBR bit-rate to get around the spikes in the VBR codec. Under very similar test conditions the VBR failed on every take.
 
Very hard to say, VBR is more efficient but there are more extreme fluctuations in the amount of compression applied.
 
I've just tested my new Hoodman RAW 675X 4gb card today.
I crank up to 990% at CBR and shoot straight for 10 mins without any problems
Then I tried VBR to -16, same it has been so smooth and there is no buffer icon comes up or anything.
Can you please show me to how to check the bitrate of the clips? I would like to check the peak bitrate in VBR and peak bitrate in CBR. Thanks
 
it's so weird, at CBR 990% i only get 59mbit/s, VBR at -16 is roughly around 36mbit/s ( really close to the default canon)...... i must have done something wrong
 
The CBR maxes out at about 80Mbit/s, doesn't matter how much higher you go over about 180%. If there isn't a lot of detail in a scene the bit-rate will be lower. harsh sunlight a wide lens and grass or foliage is a good test for max bit-rate.
 
Hello,

Is this higher bitrate ML still on the bleeding edge or is it stable? Also, does the CBR make the footage easier to edit in your NLE?

I am aprehensive to try a beta anything with my 5D as I use it for stills nore than and do not want to brick it.

Thanks
 
CBR is very stable compare to VBR. I have yet seen any difference between using CBR and default canon setting in editing.
 
Thanks. So is 80mbps CBR giving better images in post than the normal default? I guess I am asking is it worth it? Compression is such a weakness for this camera.

Pardon my ignorance but I can not seem to find very much info on the AJ Magic Lantern. There is a Yahoo group, a Wiki page and a Youtube video with all kinds of varying information.
I don't see a lot of talk about it compared to the original ML which had people buzzing. Any thoughts? I just want to know what I am getting into.

Thanks
 
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