AVCHD question regarding maximum file sizes/duration

[Peter Gjevre]

Hi,

I've been a lurker here since 2003 and have been using DV and HDV for awhile.

I'm thinking of making the jump to AVCHD, in part because my most recent projects (all non-pro) have required unattended cameras and I ended up losing things because tapes ran out.

I'm considering one of the canon HF series or perhaps holding out for the micro-four thirds to come out.

My basic question is, at a 17 mBps bit rate, what's the maximum size SDHC card you can put in, and approximately how many hours can a person expect (assuming an AC adapter is used for power)?

I'm mainly recording a previously defunct rock-band from multiple angles as it comes together for a 72 hour recording session. As I will be playing in the band, I will have limited attention to pay to the cameras.

Thanks in advance.

Peter Gjevre

[Michael Murie]

I checked the HF10/HF100 manual and couldn't find any specific file size limitation/length of recording mentioned; that doesn't mean there isn't one, but I couldn't find anything in my look through the manual...

It does say that in 16GB you'll get 2 hr 5 min in FXP mode, 4hrs 45 min in SP mode, and 6hr 5 min in LP mode..... whether the camera will overheat and die before that is another question.

[Nate Morse]

I've got an HF100 and my 16GB card will hold 2 hours of footage at the highest quality. The longest I've ever shot was for 1 hour straight (needed to stop to change the battery). It was a little warm afterward, but not bad.

Check Canon's website, but I believe a 32GB will work with the HF100 just fine. That would give you four hours of footage at a time.

Haven't tried it personally, but I suspect the camera could run for many hours at a time plugged into AC. It's a great little unit.

[Peter Gjevre]

So in either of your experience, has overheating been a problem with the HF series, or is it something endemic to AVCHD in general?

I'm just wondering if I would be better off just repeatedly popping tapes into some HDV cams, or maybe just doing firewire capture from a couple of HDV cams. I know the editing would be less processor intensive, but necessitating multiple firewire capture devices or laptops may also complicate things. Anyone have any experience with such a setup?

[Dave Blackhurst]

Two factors, many of the still type cameras seem to have recording time limitations for some strange reason... 30 minutes seems to pop up, supposedly something to do with whether the camera is taxed as a video camera in the EU (but that could be urban legend?)

BUT, speaking from the perspective of a Sony user of a similar video camera, the video cameras will record until the Media fills up (hours and hours in the case of a HDD camera). 8G is typically good for around an hour at highest resolution, 16G about double that. Most of the time a big battery will last longer than the media...


AVCHD does break the files into shorter 2G files that are usually stitched together by the included software when imported into your computer. But that's a technical thing, and you end up with one big file as far as playback from the camera or download to the computer is concerned.

[Peter Gjevre]

Interesting. I hadn't thought about the HDD type AVCHD cams, I might have to look into them, particularly if they do 24p in some form or another. For this particular project, full manual and DOF issues aren't as big of a deal, especially since no one will be operating them.

Six months back, when we had the first reunion of the band in approximately 16 years, the limiting factors were the poor low light of the panny and the fact that the tapes ran out without anyone noticing. I've been editing the footage for the past month or so, and have found to my dissapointment that many songs are simply cut off half-way through because of this. The HV10 performed remarkably well which is what got me thinking about other canons, but I'm really open to any tools that will help us get the job done.

Thanks again,

Peter

[Robin Davies-Rollinson]

Peter, I've got a couple of 32Gb cards for my HF10 and they are fine. I've never shot continuously with them, but I can see no reason why not (with the mains adapter , of course, since you're looking at over four hours of recording here and the battery won't cope with that!)

[Michael Murie]

So far I haven't run the HF100 for more than an hour, so can't speak to it's performance over longer periods.

The only reason I brought it up is that I have a Sony TRV-900 (DV tape camera) that after two hours of constant use developed a stuck pixel on the imager. Problem was gone the next day.

AVCHD does break the files into shorter 2G files

That's a limitation of the file system used by the camera, not AVCHD.

[Peter Gjevre]

That's very encouraging to hear. Any thoughts on low light with this setup? Would I be better off getting a pair of HFS100s with the theoretically improved low-light capabilities, or would a couple of HF100s or HF10s do just as well?

For reference, the HV10 which I used last summer seemed to do just fine in the recording studio, wheras the DV953 (similar to the GS100) had it's share of problems. I believe the sensor in HV10 is the same as the HV30.

Thanks,

Peter

[Peter Gjevre]

Michael,

Would it be fair to theorize that the stuck pixel thing could happen then with just about any camera regardless of codec or media?

[Michael Murie]

Originally Posted by Peter Gjevre

Would it be fair to theorize that the stuck pixel thing could happen then with just about any camera regardless of codec or media?

I'm not qualified to theorize...more like wildly speculate!

But, heat can be an enemy; it can increase noise in the image, and perhaps cause other sensor problems. The link below has an example of a "Dark Image" that shows how noise increases by a factor of 5 after 10 minutes of continuous shooting with the Canon 5D mark II. Now the 5D Mark II is a digital still camera, so is probably less engineered for running for long periods than a true video camera is, and the dark images are an extreme test, but it does point to possible problems. EOS40D / EOS50D comparison


Again, I'm speculating wildly, but your application (leaving the camera running all day long) would probably be classified as an extreme situation for these cameras. Perhaps you can find someone that's done similar things - with the camera you want to use - and can report how it went.

Having sowed the seeds of doubt, it may be worrying over nothing; there are definitely cameras out there that run for hours and hours with no problem (like security cameras, etc.) but having had my own experiences, if I was going to be recording something I wanted to be sure to record, then I'd either check that others have used the camera for hours at a time without problem, or do some tests beforehand, or rest the cameras every few hours.

[Michael Murie]

Originally Posted by Peter Gjevre

That's very encouraging to hear. Any thoughts on low light with this setup? Would I be better off getting a pair of HFS100s with the theoretically improved low-light capabilities, or would a couple of HF100s or HF10s do just as well?

If you were happy with the HV10, then I think you'll be just as - maybe even more - happy with the HF100. For a small, single chip camera I think it does pretty well (though indications are that the HFS10/HFS100 is going to do even better in low light.)

When I compare the HF100 to a three-chip camera that does well in low light, the HF10 has a tiny bit more noise, and the color is noticeably not as rich; but it's still a very useable image (and at less than 1/5 the price!) Now if the HFS100 turns out to be almost as good as the three-chip camera, it will be worth the extra money, but if it's only a marginal improvement, I'm sticking with the HF100!

By the way, if you have a choice, I'd get the HF100 over the HF10. Many people find it easier to copy files from the SD cards using a card reader to a computer for editing, than using the internal memory that you get in the HF10.

Canon HV10 Camcorder Review - Canon HDV Camcorders
Canon Vixia HF10 Camcorder Review - Canon Flash Memory

[Peter Gjevre]

Low light is important, but since we're going for a kind of pseudo documentary/rock/mockumentary type feel, and since we've embraced Lo-Fi production techniques historically (even though we're using a pro tools/logic rig for audio these days), I personally find the trade-offs acceptable. In fact, I've been introducing fake film noise to the clips from last summer and find it visually appealing for what we're trying to do. On the other hand, the generally grainy-ness of the DV953 footage has been less acceptable for our goal.

I really appreciate all of your input. I guess I need to decide whether scooping up a couple of hf100s before they dissapear is the way to go versus waiting for the hf S100s to become less bleeding edge (pricewise).

Thanks for all your input.

Peter

[Tom Gull]

Originally Posted by Michael Murie

I'm not qualified to theorize...more like wildly speculate!

But, heat can be an enemy; it can increase noise in the image, and perhaps cause other sensor problems. ........

Having sowed the seeds of doubt, it may be worrying over nothing; there are definitely cameras out there that run for hours and hours with no problem (like security cameras, etc.) but having had my own experiences, if I was going to be recording something I wanted to be sure to record, then I'd either check that others have used the camera for hours at a time without problem, or do some tests beforehand, or rest the cameras every few hours.

I've recorded pickup soccer games outdoors 4-5 times, close to 2 hours each time. Air temps ranged from about 85 degrees down to maybe 50 for the last time. This was with a Sony CX12 mounted on a tripod - heat buildup never even crossed my mind and the camera certainly wasn't warm enough when I dismounted it to have any memory of unusual temps. The manual mentions that the camcorder will produce a little heat but I've never noticed any.

[Peter Gjevre]

That's good to hear, Tom.