Thoughts on where future Magic Lantern updates for the T3i are going?

[M. Gilden]

Monitoring

Has always been possible indirectly on the t3i with a signal splitting setup, but you have to watch what levels go into the camera pretty closely, but this applies to the t2i too. Splitting the signal means you have to tweak things for the impedance of your headphones/amp, so it's more tricky on the t3i, but possible

This is less than ideal. Every connection point, especially when dealing with 1/8" minijack plugs, is a possible source of noise. You always want to monitor at the *last* point possible, ideally out of the camera instead of before it hits the camera.
Just to illustrate- I've had shoots back in my DVX days that I didn't monitor during filming, but rather relied on my on-screen meter to determine that the mic was still working and that the levels were good.
What I didn't realize, however, was that the cable going into the camera has been worn and now had a weak connection, causing a lot of static whenever it was moved. Whenever the camera would pan or I would lightly adjust something, a lot of static was immediately obvious. I didn't know it was there until watching the clips in post.
If I had monitored properly, I would have caught it right away, saving the shot. But I wouldn't have known that if I had split the sound to monitor before the camera, as the problem was actually the *last* link in the chain.

AGC

Can be disabled on the t3i natively.

Manual gain

Yes, can be controlled natively on the t3i, but how about digital gain? ML lets you control this too. Is there any evidence that digital gain is being applied in the camera?

According to A1ex, setting the manual gain on the stock Canon firmware is adjusting *only* the digital gain. Which is about as useful as adding gain in post.
Using ML, you can actually set the analog gain somewhat; the chip appears to only have a handful of exact db gain options, with no in-betweens. This is likely why the camera has to resort to digital gain to get precise volume levels. Using Magic Lantern, you can ensure that the digital gains stay off, and adjust as necessary to get the cleanest sound possible.

Performance of new audio chip

Has anyone done any thorough testing of the t3i using the best possible equipment (Juiced link, decent mics?). How does the noise floor compare?

I would be interested in seeing this as well. But I imagine it would be difficult to compare, since using ML on a t2i will give precise audio control whereas the T3i will only give you digital. Without being able to test both in the exact situations, it might be difficult to test. But I would love to see someone conduct something and post some numbers.

 

[jamesd256]

This is less than ideal. Every connection point, especially when dealing with 1/8" minijack plugs, is a possible source of noise. You always want to monitor at the *last* point possible, ideally out of the camera instead of before it hits the camera.
Just to illustrate- I've had shoots back in my DVX days that I didn't monitor during filming, but rather relied on my on-screen meter to determine that the mic was still working and that the levels were good.
What I didn't realize, however, was that the cable going into the camera has been worn and now had a weak connection, causing a lot of static whenever it was moved. Whenever the camera would pan or I would lightly adjust something, a lot of static was immediately obvious. I didn't know it was there until watching the clips in post.
If I had monitored properly, I would have caught it right away, saving the shot. But I wouldn't have known that if I had split the sound to monitor before the camera, as the problem was actually the *last* link in the chain.

Well my main concern is not a crackly lead between pre-amp and camera. It's mainly about what is coming in to the mic, so for the most part I can live with the limitation you correctly highlight. It's still a world better than no monitoring.

According to A1ex, setting the manual gain on the stock Canon firmware is adjusting *only* the digital gain. Which is about as useful as adding gain in post.
Using ML, you can actually set the analog gain somewhat; the chip appears to only have a handful of exact db gain options, with no in-betweens. This is likely why the camera has to resort to digital gain to get precise volume levels. Using Magic Lantern, you can ensure that the digital gains stay off, and adjust as necessary to get the cleanest sound possible.

The only comment on t3i audio I can remember from Alex is this one:

http://www.dvxuser.com/V6/showthrea...udio-problem&p=2403053&viewfull=1#post2403053

Maybe you could dig out any further comments I've missed.

I would be interested in seeing this as well. But I imagine it would be difficult to compare, since using ML on a t2i will give precise audio control whereas the T3i will only give you digital. Without being able to test both in the exact situations, it might be difficult to test. But I would love to see someone conduct something and post some numbers.

If I ever get the t3i I will endeavour to do some tests, as there seems to be a lack of in depth research on the subject. From reading about the 60d situation, I imagine that it's not just digital gain, and putting a hot signal in can get you a reasonable noise floor. If you know for sure otherwise, I am all ears. Tests have been done with that camera which reveal it's not a simple matter of digital only gain. I am also fairly clear it will never be as good as the t2i with ML - Jon Fairhurst did some test which show you can get a lower noise floor than the zoom h4 using a juicedlink. Until the chip is identified/documented/reverse engineered, the t2i wins for sure.

 

[M. Gilden]

Well my main concern is not a crackly lead between pre-amp and camera. It's mainly about what is coming in to the mic, so for the most part I can live with the limitation you correctly highlight. It's still a world better than no monitoring.

Yes, but your solution sort of goes without saying- of course you can monitor the source before it hits the camera. The breakthrough here was that you could actually monitor the audio from the recording medium, which how it is supposed to be done.

If I ever get the t3i I will endeavour to do some tests, as there seems to be a lack of in depth research on the subject. From reading about the 60d situation, I imagine that it's not just digital gain, and putting a hot signal in can get you a reasonable noise floor. If you know for sure otherwise, I am all ears. Tests have been done with that camera which reveal it's not a simple matter of digital only gain. I am also fairly clear it will never be as good as the t2i with ML - Jon Fairhurst did some test which show you can get a lower noise floor than the zoom h4 using a juicedlink. Until the chip is identified/documented/reverse engineered, the t2i wins for sure.

I don't have any links to specific posts at the moment, but I recall A1ex saying that Canon's version of "manual gain control" only adjusted digital gain. It might have been on his google group or maybe in a private conversation we had. This was regarding the 60D and presumably the t3i as well.

The problem with the analog gain is that it appears to only have very specific values it can be set to. For example, it appears to go from 0db (off) straight to 10db, and then 17. That doesn't give a lot of precise control, especially if you only need a slight boost of +8db.
What I've found is that I need to leave the gains at zero and boost the signal before it hits the camera (with a juiced link or sennheiser amp). That's likely the advice you've been seeing.

 

[damiaanp]

my friend made breathtaking music video with nikon d5000 without many options you have even in "stock" 550d.. It really doesn't matter what do you choose in this price-range, 600d = articulating screen witch is VERY important for me