'Write Speed' indicater changing value .....

Started by [email protected], February 21, 2020, 03:17:48 PM

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[email protected]

Greetings ..... Could someone kindly tell me why this *read-out* (please see pic) - is sometimes high (like 39.2 MB/sec) and at other times low (like 32 MB/sec) - or anywhere in between. It seems as though every time I turn on the 70D, my expected recording time can vary considerably. eg: A RAW file might sometimes yield 17 seconds or 25 seconds or even 30 seconds, yet the 'settings' have not been altered. It's just that the currently estimated 'write speed' varies so much. It's the yellow message that reads (for example) "Expect 694-780 frames at 38.3MB/s"  (please see pic).

Thankyou  :)

https://www.dropbox.com/s/s22ehidafouslw5/Write%20Speed%20changing.jpg?dl=0

KirbyLikes525

Write speeds (or any data transmission) aren't constant and depend on a lot of factors you can't control and even vary between cards themselves of the same line. I have a CF San Disk Extreme Pro that will write upwards to a minute at full 14bit ML Raw but my other cards, same model and capacity, come nowhere close varying between 20s - 30s per capture.

But if you want a reliable continuous record then I suggest the 10/12 Bit RAW video experimental build found on the https://builds.magiclantern.fm/experiments.html page for your 70D. On my Mark II, I get continuous record for 24fps @ 12bit but only continuous record for 30fps @ 10 bit. However, even the 10 bit still looks gorgeous, in my opinion - believe me, you're not losing much with the eye test. I'm working on a 10bit project now that I'll be sharing soon the Share forum.
5D Mark II
10 bit 12 bit Experimental Build

yourboylloyd

Quote from: [email protected] on February 21, 2020, 03:17:48 PM
Greetings ..... Could someone kindly tell me why this *read-out* (please see pic) - is sometimes high (like 39.2 MB/sec) and at other times low (like 32 MB/sec) - or anywhere in between
https://www.dropbox.com/s/s22ehidafouslw5/Write%20Speed%20changing.jpg?dl=0

Yeah that value changes all the time honestly. I just got used to it. What's helpful is if you use this calculator for your 70D https://rawcalculator.netlify.com/calculator_desktop
Join the ML discord! https://discord.gg/H7h6rfq

[email protected]

Hey, thanks very much for your quick replies!

@KirbyLikes525 .....
Yes, I'd purchased 3 identical 'Samsung EVO Plus 64GB micro SD cards' from ebay at a really good price. But I was careful they weren't fakes - and I'm certain they're genuine. So because I'm 'new' to Magic Lantern, I started thinking it was either my 70D or the SD card at fault, so I posted the above query. Then I discovered that the *other 2 cards* were a lot better, they were consistently showing write speeds of 39.3 to 39.5 MB/sec. So I did the following:

● swapped the faulty card into several other adapters, (the problem remained)
● cleaned the copper contacts of the the mico-SD card using pure alcohol. (the problerm remained)
● ran a 'speed' test on it usng 'the free tester H2testw'. It showed a consistant 63.5 MB/sec write speed (the card was fine - it's rated at 60B/s)
● decided to remove M/L and again format the card in the camera, then reinstalled M/L (the problem remained)
● decided to format the card in the PC instead, this time doing a FULL (slow) format, rather than a 'quick' one. Reinstalled M/L and tried again.
● Voila! - the card returned a write speed of 39.3 MB/sec just like the others.

Conclusion: I'm thinking that every time I fill a card with video, I'll dump the files to my PC, then do a proper *full* format of the card, then re-copy the M/L files to it again, and re-initiate M/L on the camera for that card, ready for next use. It's a bit of extra work, but it may be worth it for the sake of predictable recording times.

Kirby, - it turns out that the 10/12 Bit RAW video experimental is the build I'm actually using! - yes and I love it !!!! --- Hey - and you're getting some really great recording times on your Canon! - better than on the 70D. I've tried 10bit and saw a definite improvement. I had a play with 12 and 14 as well. I found the 14 bit is too demanding on the 70D (for Full Frame - and I'm not that keen on using 3x crop). And I do like the 12 bit - though again it's still intense on data. At the highest available resolution of 1832 x 780, I can get around 25 seconds of recording time (that's 2.35:1 using 24fps) - I'm very happy with that since 25 seconds is ample for most shots. Hey Kirby, I'll be keen to check out your project for sure!



@yourboylloyd ....
Thanks for that link - yes, I'm wondering whether this idea of fully fornatting the SD card is maybe the answer. I'm still too new to say. I read online that when you do a quick format, it only erases the 'adresses' to where your data is located on the card - but that it doesn't erase the data itself (until you record over the next time). I'm thinking this *may* affect the future 'writes' causing a bit of a bottle neck. I also read that some SD cards (like the Samsung EVO I'm using), are 'optimized' for continuous (sequential) writing. That makes me think that a fresh, properly formatted card is maybe best each time it's re-used. All I know is that it worked in my particular case, and I'm so glad it did because I was close to throwing the card away thinking it was faulty ....