20Mar Preparing for the Panasonic GH4 – Memory cards
I have a few Sandisk Extreme Pro SD cards laying around as well as some less “pro” Extreme cards. I spent some time today working through the math and speed testing to see if any of these cards would keep up with Panasonic Gh4’s 4k recording function. In order to save you guys some time I figured I go through it here for future reference.
According the spec sheet, the Panasonic Gh4 captures 4k footage at up to 200mbps which is equal to 25MB per second. If you aren’t big into tech you can find out more about bits vs Bytes here. A 64GB card, when formated, gives a little bit less than 60GB of usable space but i’m going to round to 60GB because it’s pretty close. 60GB equals 61440MB so if you are writing to the card at 25MB per second you’ll want to divide 61440MB by 25 which gives you 2457.6 seconds of recording time or about 40 minutes (40.96 to be exact) of recording time on a 64GB card at 4k. So here’s how it works out.
200mbps data rate recording times for 4k (unknown see update) and 1080p
- 16GB = approximately 10 minutes of record time at 4k
- 32GB = approximately 20 minutes of record time at 4k
- 64GB = approximately 40 minutes of record time at 4k
- 128GB = approximately 80 minutes of record time at 4k
- 256GB = approximately 160 minutes of record time at 4k
100mbps data rate recording times for 4k and 1080p
- 16GB = approximately 20 minutes of record time at 4k
- 32GB = approximately 40 minutes of record time at 4k
- 64GB = approximately 80 minutes of record time at 4k
- 128GB = approximately 160 minutes of record time at 4k
- 256GB = approximately 320 minutes of record time at 4k
So will my Sandisk Extreme cards be able to handle 4k? The answer is maybe. While the Sandisk Extreme has an average write speed of 42.47MB/s in CrystalDiskMark, that’s only an average. If at any point during that test the card dropped below 25MB/s it might not be fast enough and you could end up stopping a recording. Don’t get me wrong a 42.47MB/s average is pretty good and you might be able to record 4k all day long at that speed depending on the buffer size in the Gh4, but it’s a low enough number that it could conceivably drop below 25MB/s at some point during a shoot.
The Sandisk Extreme Pro test tells a happier story. With an average write speed of 70.95MB/s the card would have to dip below 35% of it’s average write speed before it stopped a 4k recording. The Sandisk Extreme Pro cards are most likely fast enough to handle 4k recording on the Panasonic Gh4. This is nice when you consider that 32GB Sandisk Extreme Pro SD card are around $49, compared to the new Extreme PRO UHS-II 32GB cards at $130 a piece.
One thing to note is that Sandisk says “up to 90MB/s writes” on the Sandisk Extreme Pro cards, but they say “a minimum sustained write speed of 30MB/s” on the more expensive Extreme PRO UHS-II cards. This probably means they’ll guarantee the more expensive cards will work and leave you hanging if you have any issues with the older Sandisk Extreme Pro cards. I guess “Pro” means something different than “PRO”.
UPDATE: A few of you have mentioned that 4k recording is only in 100mbps mode. This might be the case, the answer I received from Pansonic was that “4k requires a card with a minimum sustained write speed of 30MB/s” which is actually 240mbps I assumed the extra 40mbps was a built in margin of error, but I could be wrong. Also in this interview with Panasonic at about 6:49 in the video he says 100mbps and 200mbps after talking about 4k. Maybe this only refers to 1080, but it seemed like he was implying 4k as well. If you look at the Panasonic GH4 speck sheet here at the beginning of each list is “[4K] 3840×2160:29.97p,” after the comma it lists another bit rate and format, but there isn’t any bit rate listed with the first format. Maybe this is referring to external recording formats but it’s not specified. If anyone gets a definite answer let me know and I’ll update the post again.
March 21st, 2014 at 12:24 am
4K only does 100mbps to a card.
March 21st, 2014 at 8:51 am
I could be wrong, but in this interview with Panasonic at about 6:49 in the video he says “at 100mbps and 200mbps in 4k and 1080”. Thanks for the heads up Joseph!
May 1st, 2014 at 9:40 am
This is from the Panasonic website. “The Panasonic LUMIX DMC-GH4 continues to evolve delivering professional quality video. Take advantage of 4K (Cinema 4K: 4096×2160 / 24 fps and QFHD 4K: 3840×2160 / up to 30 fps) video recording in MOV/MP4, or ultra high bitrate video recording at 200 Mbps (ALL-Intra) or 100 Mbps (IPB) without a recording time limit.*1 *2 Discover a variety of high-end functions for professional video recording. “
March 21st, 2014 at 1:47 am
Interesting read, thanks for sharing this. But at 200mbps on GH4 (high bitrate mode on camera), you will need the 280mbps speed of the new UHS-II cards. 64gbs are 260 USD each.
For use its not worth the risk to use slow or even just fast enough cards. Right tool for the job means we going for 3 of the UHS-II u3 64gb cards for our bag, which should ensure hassle free filming without stress of worrying about buffer clogging due to slow cards.
March 21st, 2014 at 8:49 am
John, the 280 cards are “MB/s” not “mbps”. If they were “mbps” they’d they’d only read and write at 35MB/s which is actually slower than the Sandisk Extreme card tested here.
March 21st, 2014 at 2:12 am
Hey, just a quick heads up–everywhere I’ve read prior to now states that 1080p is up to 200mbps but 4k is only up to 100mbps. Thanks for sharing the math and memory card tests! Cheers.
March 21st, 2014 at 8:46 am
I could be wrong, but in this interview with Panasonic at about 6:49 in the video he says “at 100mbps and 200mbps in 4k and 1080”. Thanks for the heads up Samuel!
March 21st, 2014 at 11:38 am
I have used the pre-production GH4 and 4K is only 100mbps only. I was able to get reliable results with a Sony SDHC1 U1 class10 94MB/s 16GB. I do not have the SandDisk Extreme Pro. The Extreme SDHC1 U1 class10 45MB/s 32GB were not fast enough. I guess I will be buying new cards.
March 21st, 2014 at 12:07 pm
Thanks for the heads up Alan. I’ll add your comment to the post. Any test footage uploaded?
March 21st, 2014 at 11:25 pm
It’s pretty clear on the GH4’s specs on Panasonic’s USA site. All 4k modes are 100mbps, while 200mbps is reserved for 1080p.
Panasonic also states U3 speed class cards for guaranteed recording, so that would be the best option for people buying new cards. It’s similar to class 10 cards being required current cameras– while class 6 cards (and even class 4 in a pinch) would generally work, high-motion scenes could cause a spike and the camera would stop recording.
Prices might be steep for the right cards at the moment, but they’ll come down quite quickly I’m guessing.
March 22nd, 2014 at 12:14 am
Sol, here’s an example from the spec sheet “[4K] 3840×2160:29.97p, 100Mbps (IPB) (LPCM) / [4K] 3840×2160:23.98p,” while the second 4k format say 100Mbps data rates, the one in front of it does not. Any idea way?
March 22nd, 2014 at 10:05 pm
Ah, I think the comma might be throwing you off. The specs state the resolution followed by the data rate, not the other way around 🙂
April 18th, 2014 at 12:28 pm
I have the golden san disk extreme, the same on your photo above.
Do you think this one would be fast enough for the 1080p 200mbps mode?
April 18th, 2014 at 12:44 pm
The 95mb/s card I was using seemed to work well on both 1080p 200mbps and 4k. Keep in mind I was only able to play with the camera for about an hour so there could still be drop outs at 200mbps over longer recording periods.
April 27th, 2014 at 3:53 pm
Check out the brand new kingston U3 card – they shoud be good and cheep – just like we like it 🙂
May 2nd, 2014 at 12:33 am
The Panasonic rep was using a Kingston U3 card when he was doing a demo for Zacuto. They’re around $100..
May 2nd, 2014 at 12:36 am
For the 64GB card.
December 16th, 2014 at 9:11 am
I am using the Panasonic GH4 and I have 2 64 GB cards. One Transcend R95 W60mb/s and one SanDisk Extreme Pro. Both work great with the camera.
Recording Time: 1 hour and 30 min at 3840X2160 29.976fps 100mbs
Recording times have varied slightly up or down depending on what I am recording. But I have consistently gotten up to at least 1 hour and 20 min on one 64 GB card.
(At the time of this comment) The 128 GB card did NOT work well in this camera. After a min of recording or so it seems to not recognize the card anymore and stops recording. Hopefully Panasonic changes this in a firmware update someday.