Sdhc cards

Oh man, these threads give me a headache! I mean, shoot.... I gotta use all my fingers, all my toes and drop my trousers just to count up to 23!!!! (.... Think about it.... Think about it!!!). :grin:
 
cheezweezl said:
congrats, you get your wish. AVCHD may max out at 28Mbps but that would be in it's playback format. The FS100 records 60fps S&Q at 60Mbps with the intention of a file that plays back at 24Mbps. That's why you need class 10 cards to do it.

I just did the test so I could reassure myself and others. I recorded 10 seconds (roughly, by my iphone's stopwatch) of 1080p/60 28Mbps, and then 1080p/24 24Mbps overcranked to 60 frames.

the two files which contain the same number of frames (+/- 10% for human error), are completely different when it comes to file size. the 1080p/60 file is 35.9MB. The 1080p24 file is 76MB.

So, lets translate that file size to bit rate. 76MB x 8 = 608Mb. Then, 608Mb ÷ 10sec = 60.8Mbps. Now I can't claim to have recorded exactly 10 seconds, But I can say with confidence that I was off by less than one second. So this all adds up to 60frame overcrank at 24p FX records at 60Mbps.

And just in case you were wondering. If I do the same math on the 1080p/60 file, it comes out to 28.72Mbps. Exactly what it should be.




1080/60P or 1080/24P overcranked to 60? If it's 24p, then that is good news for all of us. class 6 cards are dirt cheap!!! If it was 1080/60P, you can actually do that with a class 4 card, according to sony...
Click to expand...


Like you said .. "the 1080p/60 file is 35.9MB"
the 60P file is 287mb/10 seconds = 28mbps
So 28 mbps for a file that have 60 frames on a full second, well ¿?
That means each frame on 1080p60 -if a second have 60 frames- is 0.46megabit per frame
so:
1080p60 equal -0.5mb per frame
1080p24 equal +-1mb per frame

Or is there're some i missing ¿?
 
Tony Hernandez said:
Like you said .. "the 1080p/60 file is 35.9MB"
the 60P file is 287mb/10 seconds = 28mbps
So 28 mbps for a file that have 60 frames on a full second, well ¿?
That means each frame on 1080p60 -if a second have 60 frames- is 0.46megabit per frame
so:
1080p60 equal -0.5mb per frame
1080p24 equal +-1mb per frame

Or is there're some i missing ¿?
Click to expand...


no you got it right. if you shoot 1080p/60, it's only 28Mbps or .46666Mb per frame. 1080p/24 is 24Mbps or 1Mb per frame.

The important point is that if you record 60fps using the S&Q option while set to 24p, it records at 60Mpbs so that when you play back the slow motion, your 24Mbps data rate is maintained.

In other words, when you are recording 24p and you overcrank to 60 frames, there is ZERO loss in quality.
 
So why you tell me some time ago that im not true.
I was said that recording at 60P (1080p60) on FS100, have less quality than recording at 1080p24, and your file your comments and the ones by me then confirms that.

I dont like to have to use the Overcranking feature instead of default rec. for the 60P to have not less quality.

And another thing that i suspect is related to the overcranking feature.
Yet as for to know if that using the S&Q will be really mantain the quality, tell me:
Does the clips recorded at S&Q feature for slow motion (60P) from 24P mode, have 60 frames per second ? or only have really 24 frames in each second ?

Cause i think that starting from a 24p rec. mode, starts a 24fps rec. mode, and even doing slow motion, the frames maybe 24p on file, can you reply the above question ..
Your reply may allow to determine if as for mantain the quality in 60p, then the camera need to start from 24p then do slow motion feature, or anyway the quality wil be less for 60p.
 
Tony Hernandez said:
So why you tell me some time ago that im not true.
I was said that recording at 60P (1080p60) on FS100, have less quality than recording at 1080p24, and your file your comments and the ones by me then confirms that.

I dont like to have to use the Overcranking feature instead of default rec. for the 60P to have not less quality.

And another thing that i suspect is related to the overcranking feature.
Yet as for to know if that using the S&Q will be really mantain the quality, tell me:
Does the clips recorded at S&Q feature for slow motion (60P) from 24P mode, have 60 frames per second ? or only have really 24 frames in each second ?

Cause i think that starting from a 24p rec. mode, starts a 24fps rec. mode, and even doing slow motion, the frames maybe 24p on file, can you reply the above question ..
Your reply may allow to determine if as for mantain the quality in 60p, then the camera need to start from 24p then do slow motion feature, or anyway the quality wil be less for 60p.
Click to expand...

1. i'm not the one who said you were wrong.

2. we are talking about overcranking maintaining 24Mbps quality. we were never talking about quality of native 60p vs. native 24p. it's obvious that native 60p is less quality and not worth debating.

3. my comments and calculations were for anyone saying that when overcranking, the quality would not be as good.

4. i'm not quite sure what your goal is or even what you are asking me, but maybe this will help. overcranking is NOT the same as recording at 60p native. no sound and you end up with a 24fps, slow motion clip. however, it is recorded at a much higher bit rate than 60p native so if sound isn't important to you, you could always take that 24p slow motion clip and conform it to 60p using cinema tools or something. then you would have true 60p, at the best quality but with no sound.

5. my head hurts.
 
dustylense said:
LOL! Guys, megaBITS and megaBYTEs are two very different things. You could shoot AVCHD on class 4 cards. Cheez, 60Mbs is is 7.5 megaBYTES/sec. Where those class 10 cards come in handy for AVCHD is transferring your footage.
Here is a calculator for you all to use: http://www.translatorscafe.com/cafe/units-converter/data-storage/calculator/megabit-to-megabyte/
Click to expand...

Class 4 cards have speed of 4MB/s which is good for regular HD recording. But for S&Q Motion recording class 10 is recommended. Some of the class 6 cards might be fast enough to handle S&Q. If you've spent $5k on a camera, you can afford couple of class 10 cards.
 
dustylense said:
LOL! Guys, megaBITS and megaBYTEs are two very different things. You could shoot AVCHD on class 4 cards. Cheez, 60Mbs is is 7.5 megaBYTES/sec.
Click to expand...

Yup. I know the diff between a bit and a byte. 8 bits in a byte. All my math on this thread reflects that.

With that said, I can reliably record 48fps overcrank on my ex1 on a class 6 card. That comes in at 8.75MB/s. So based on this, I could probably get away with using my old class 6 cards on the fs100 in S&Q. However, my class 6 cards are fast. Faster than some other cards badged as class 6. So I can see why Sony says to go for class 10 cards. That way, even the slower of the bunch can still pull it off.

Either way a new class 10 16GB card is $26. If you're too broke to swing that, you probably shouldn't be buying a camera. Maybe think about getting some lunch first. lol...
 
Tony Hernandez said:
AVCHD is max at 24mbps, sony implements up to 28mbps for 60p.
This means 28 divided by 60 frames, this means that to have the same quality as for 24P it need to be rated at 60mbps and not 28mbps like sony mentions on its specs, this means -over my tech. point of view- that recoding at 60P have 0.466Mb per frame like you write.

So and as notice:
24P 24Mbps = 1Mb per frame.
60P 28Mbps = 0.47Mb per frame.

So at 60P the quality per frame is inferior.

I hope to be wrong, i wish, but maths
Click to expand...

Remember that perceived image quality has to do with 1) Spatial Resolution (pixels/color) and 2) Temporal Resolution (respect to time; frame rate).

Therefore in theory 60p should give a higher perceived quality due to it's inherent higher Temporal Resolution over 24p.

However as you pointed out, each frame should get HALF the dedicated throughput of data when recording in 60p than in 24p (with the FS100 implementation of AVCHD).

HOWEVER, keep in mind that this might be offset by the fact that we have increased Temporal Resolution by 2.5 times over 24p.

Also the compression level of AVCHD may reach a plateau where the human eye can no longer easily perceive the difference in image quality due to compression. This may be supported by the fact that 24Mbps AVCHD off of the FS100 have been compared to footage recorded to ProRes422 HQ @ 220Mbps and the perceptive difference is negligible to the naked eye.
 
To be fair, Ive been to busy to throw any of this footage on the resolve as of yet. So i cant speak to the 28mbps with any real world experience. But you can grade pretty much any footage that has been properly exposed. It's those shots that have serious problems or shots that are underexposed to preserve highlights that will separate the men from the boys, codec-wise.
 
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