funkytwig Posted December 31, 2012 Share Posted December 31, 2012 I has just got a GH3 and in the manual is gives MBPS (mega-bits per second) as the data rate for the various recording formats but does not say how much video can be recorder per MB. I have therefore tried to work out the MB/s for these formats and how much video they can record on a 32GB card. I am doing this for 50 MBPS (MOV FHD/50P) but the same logic can be applied to other data-rates. First I need to convert MBPS to MB/s, I believe I have to divide MBPS by 8 to get this. Then I need to know how many MB there are in 32GB which is 32*1024 = 32768 Then I need to work out how many seconds the card will record ( 32768 / MB/s )I then divide by 60 to get how many minutes the card records. So here is the calculation 50 MBPS / 8 = 6.25 MB/s (I.e. any class 10 card should be fast enough) 32768 / 6.25 = 5242.88 seconds / 60 = 87.38 minutes So a 32GB card can record 87.38 minutes of video at a data-rate of 50 MBPS. (I did the same calculation for 28 MBPS (AVCHD 50P) and got 156.04 minutes) Does this sound correct? Ben Quote Link to comment Share on other sites More sharing options...
powderbanks Posted December 31, 2012 Share Posted December 31, 2012 i know with my gh2 i get ~60min on a 64gb card. but that is also hacked. on the gh1, hacked, i could get ~2hours on a 32gb card. and the data-rate the gh3 uses, i'm 99% sure is a variable bit rate, so it's only going to be hitting 50mbps in super high detail, well lit scenes. the rest of the time it'll probably much lower. so i'd say your math is pretty close. i just did it for a 176Mbps patch with a 64gb card and came up with 49.65 minutes. which seems about right, because that is assuming a cbr of 176Mbps. Quote Link to comment Share on other sites More sharing options...
nahua Posted December 31, 2012 Share Posted December 31, 2012 Your calculation is very good. BTW take a look at this thread: http://www.eoshd.com/comments/topic/1692-memory-cards-panasonic-gh3/ Quote Link to comment Share on other sites More sharing options...
jgharding Posted January 8, 2013 Share Posted January 8, 2013 If it's VBR very dark scenes where you've used high ISO will also crank up the rate. Encoding all the dancing ISO noise takes a lot of data. The higher the bitrate, the more distinct each noise grain and the easier it is to denoise Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.