View Full Version : 16 gb card recording time
Martin Doppelbauer August 16th, 2011, 10:30 PM Sounds like a silly question: What is the recording time you get out of an 16 gb card in 35 mbit VBR mode?
I am using SanDisc Extreme cards and the display of my XF 100 camcorder says 57 mins after the initialization of the card.
However, just after 45 mins of actual recording time the card is full and the camcorder switches to the other slot. I am currently on vacation and this happened already with three cards in a row.
I know there is a difference between GB and gigabytes but not that big, right?
So what is your experience with the 35mbps VBR recording mode? Can you actually use the announced 57 mins?
Steve Maller August 17th, 2011, 10:14 PM At 50mbits the camera says 41 minutes on my 16GB cards. I haven't used anything else.
Vincent Oliver August 18th, 2011, 01:07 AM So what is your experience with the 35mbps VBR recording mode? Can you actually use the announced 57 mins?
Yes, and sometimes it can be slightly longer.
The same recording times are available if you shoot 1920x1080 or 1280x720, never quite worked this one out.
Martin Doppelbauer August 19th, 2011, 06:31 PM I have just been able to look at one of the cards in my computer and it tells me there are still 3.05 GB of free space available.
However, the camcorder (XF 100) tells me the card is full (0 mins available recording time).
It is a SanDisk Extreme 16 GB card, it was initialized in the camcorder and never plugged into a computer before.
Any idea what I am missing ?
Vincent Oliver August 19th, 2011, 11:56 PM The camcorder records in 4gb chunks, at a guess it would seem like the camcorder has worked out that you do not have 4gb available, hence it will not let you record for the remaining time. I may be wrong, but I am sure someone will post the correct information.
Martin Doppelbauer August 20th, 2011, 05:43 PM This is really strange, The camcorder's status screen says "12,05 GB used; 0 mins available".
I am going to ask Canon Service when I get back home. Maybe a firmware fix will be needed to solve the issue...
Graham Bernard September 23rd, 2011, 02:05 AM Martin, did you ever resolve this?
Grazie
Rick Corben September 23rd, 2011, 10:53 AM I do not know the answer, but here is a guess.
The "problem" probably is related to the number of clips that you record on a single card. If you look at the Canon file structure, you will see that there are several "overhead" files associated with each .MXF file (which is the actual video/audio file). Space on the CF cards is allocated in chunks which are pretty large. That means that even the smallest file, say 1 byte, must use a full chunk. The "wasted" space is not much of an issue if you only have long clips (e.g., only 5 on a card). But if you have short clips, say 100 or more on the card, then the "wasted" space will add up and have an impact on the available recording time.
Martin Doppelbauer September 23rd, 2011, 02:03 PM Unfortunately I have not been able to resolve this issue. I sent a letter to Canon Service in Germany and they even forwarded it to Canon Service in Japan. In short, they have no clue what it is.
Here is a record of all my 12 cards that I have used during the last vacation.
All are SanDisk Extreme 16 GB, all are brand new and all were formatted in the camera (and only in the camera):
Card # / # Clips / Capacity / Available / Used / Loss
Card 1 / 202 / 15,98 GB / 3,58 GB / 12,39 GB / 22,4 %
Card 2 / 168 / 15,98 GB / 3,19 GB / 12,78 GB / 20,0 %
Card 3 / 161 / 15,98 GB / 3,27 GB / 12,70 GB / 20,5 %
Card 4 / 196 / 15,98 GB / 3,59 GB / 12,37 GB / 22,5 %
Card 5 / 188 / 15,98 GB / 3,70 GB / 12,27 GB / 23,2 %
Card 6 / 148 / 15,98 GB / 3,06 GB / 12,92 GB / 19,2 %
Card 7 / 145 / 15,98 GB / 3,20 GB / 12,77 GB / 20,0 %
Card 8 / 146 / 15,98 GB / 3,36 GB / 12,61 GB / 21,0 %
Card 9 / 167 / 15,98 GB / 2,58 GB / 13,39 GB / 16,2 %
Card 10 / 116 / 15,98 GB / 3,25 GB / 12,72 GB / 20,3 %
Card 11 / 154 / 15,98 GB / 3,37 GB / 12,60 GB / 21,1 %
Card 12 / 127 / 15,98 GB / 2,68 GB / 13,29 GB / 16,8 %
Avg / 160 Clips and 20,3 % Loss
All clips are marked "0 mins recording time left" in the camera. But my Mac says differently: In average more than 20% of the card's capacity goes unused.
I guess there is a problem with the firmware. Maybe a fix will be released at a later time to solve the issue.
Rick Corben September 23rd, 2011, 04:50 PM >> I guess there is a problem with the firmware. Maybe a fix will be released at a later time to solve the issue.
Not likely, I suspect. You did a great job in recording your card history. Unfortunately, it tends to reinforce my suspicion about the cause. Note that you put a large number of short clips on each card. That means there is an even larger number of small "overhead" files, each of which "wastes" most of the chuck of file space allocated to it. It looks as if that is enough to explain your "problem".
If I am correct, then Canon is not likely to have any easy fix. They would have to alter their on-card file structure (i.e., those overhead files) which would break all the programs that know how to read its current form. Or, they would have to alter the FAT32 file system which would break everything. Bottom line: Expect to live with the "problem".
Vincent Oliver September 24th, 2011, 12:38 AM Maybe it is just bad sectors on the cards. Most hard drives and memory cards will have a number of these
Martin Doppelbauer September 24th, 2011, 01:03 AM Sorry I don't quite follow the logic in the 'overhead' files explanation.
If the remaining space is taken by overhead files then why is this space freely available? Shouldn't it be reported as 'used' ?
And 160 files on a 16 Gb card is by no means an excessive number. I have well over one million files on my Mac's hard drive...
Try to align the amount of unused space with the number of files in my listing. I doesn't correlate either (i.e. the amount of unused space does not strictly follow the number of files).
Regarding the bad sectors theory: I'll try to fill the unused space with other files later today at the computer. Then we'll see if that's the problem.
Gareth Burleigh October 13th, 2011, 01:20 PM Rick is correct on this, I noticed this after a day of shooting skateboarding for a local shop. On a full 16Gb card I noticed the card read 9Gb of media the card had over 300 separate shots on it. Doing an event video one continuous file pretty much used the entire 16Gb.
Its an annoyance but at least the camera is always correct with remaining record time
Hope this helps
regards
Gareth
Vincent Oliver October 13th, 2011, 10:34 PM Each one of those clips has an index, i.e. all the info on the clip, metadata etc. I suspect that if you fill the card up with 300 clips then the space allocated for indexing will be used up, hence you can't add any more files. Whereas if you shot one long clip or a series of longer clips then you will not use up all the space that is reserved for indexing.
Just my thoughts
Gareth Burleigh October 14th, 2011, 03:02 AM I thought thats what I said, however re reading Ricks post thats not what he said.
That seems to be the case Vincent, small price to pay for what I think is an amazing camcorder
Its not the end of the world thats for sure, just a caveat for use in certain situations
Gareth
Vincent Oliver October 14th, 2011, 03:08 AM Glad you like the camera Gareth. I presume you haven't got any yellow burn marks in your viewfinder (YET)
Gareth Burleigh October 14th, 2011, 12:28 PM No not yet and its been used heavily since it was bought a couple months ago. Is it a common fault?
Vincent Oliver October 14th, 2011, 12:49 PM Maybe Canon have fixed the problem, by fitting a new viewfinder, I haven't seen a new model as yet. My one developed the problem on its first day out and has had a second helping more recently. Take a look at this post
http://www.dvinfo.net/forum/canon-xf-series-hd-camcorders/494384-viewfinder-warning-xf300-305-owners.html
Gareth Burleigh October 14th, 2011, 04:31 PM Ouch that isn't good, I'll be sure to keep a look out for it. Did Canon get this sorted for you?
Vincent Oliver October 15th, 2011, 12:55 AM No I haven't had the time to send it off. I use my Sony EX3 most of the time
Gareth Burleigh October 15th, 2011, 02:06 AM Im sure I had something similar happen to an old Sony VX, I just put it down to wear and tear. Saying that, that poor cam saw more wear and tear than most
Martin Doppelbauer October 18th, 2011, 02:24 PM Please forgive me for coming back to the original topic of this thread ;-)
In the meantime I was able to run a couple more tests.
Firstly, the memory that is reported "unused" on the cards is really freely available. I can copy any file on it (on my computer) and read it back without problems.
Secondly, when I record just ONE very long clip onto a newly initialized card it really uses (almost) all of the available space (up 56 mins and 45 secs on a 16 GB card to be precise).
Finally, I sent one of the cards to Canon service and after two weeks they returned it claiming all was ok and the behavior would be perfectly fine. They didn't offer a technical explanation, though.
My theory is, the Camera will only start recording a new clip on an "aligned" block address, probably to make maximum use of the memory block transfer feature of CF specification 5.0 (compact flash cards are accessed just like IDE hard drives using logical block addresses LBAs). In most cases, that would leave an unused gap between the blocks taken up by two consecutive clips (depending on the length of the first clip, of course).
Adding up the number of clips and all of the unused space of my twelve cards computes to a gap of 80 MBytes per clip, which should be more or less a constant for the average of a large number of clips.
When recording just some very few (long) clips onto a card, those 80 MBytes per clip wouldn't be a significant number. But in my way of recording a lot of 15 to 30 seconds clips, these losses add up considerably.
I am not too happy about loosing some 20% of the valuable capacity of those expensive CF cards but it seems that is considered "normal behavior" by Canon.
Just wondering if Sony or the others have a similar problem...
|
|