some help for setting up for video taking please

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
A couple of questions her from me which I dont understand after looking and looking on google. I did find shutter speed vs shutter frame rate which made things clearer but:-

I have seen it written that if you have the camera set to auto for the aps-c / super 35 then movie mode uses super 35 but on myA7r2 that does not happen i need to select it manually am I misunderstanding something?

also for XAVCS there are the two choices of 25p 100M and 25p 60M

25 is the frame rate ? is that correct ?

and should be matched to double the shutter speed =1/100 is that correct?

100M and 60M is the bit rate and 100 M will give a smoother video is that correct?

if that is then correct then why is there a choice?

I note that on XAVC S HD there is the choice of 50p 25p and 100p all at 50M compared to the XAVCS which only offer 25p

So why is there a choice 3 frame rates avaialble for the XAVC S format?
 

bdbits

Super Moderator
Joined
Sep 10, 2015
Messages
2,428
Real Name
Bob
I am not a big video person, but from what I do think I know...

For 25p the '25' is the frame rate - 25 fps, p for 'progressive' as opposed to 'interlaced' frames. Usually you want progressive even if that means a lower frame rate, and shutter speed should be double the frame rate (1/50 for 25p). They say different frame rates give a different look to the video, but I have never run side-by-sides to see for myself. Oddly enough higher is not always better. I usually see 24fps recommended (what is used for movie film). The argument is that this is what people are used to watching movies in, and the different motion blur and what have you at other frame rates looks artificial.

The bit rates are more about image quality. Sort of like megapixels for stills, I suppose. The reason for choices relates to file size and the ability to play it back smoothly. It would also matter depending on how you would be delivering the video - over the internet, DVD, Bluray, local computer, etc. If you record at 100M but it will be delivered at 25M, you may have to re-encode the video. You should probably also consider the resolution - 4k video is going to need a higher bit rate to achieve a certain image quality level as opposed to say standard HD, whereas 100M might be super-high IQ for standard HD. But I have not done the math so not sure what the recommended bit rates are.

And that is about the limit of my knowledge of video.
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #3
I seem to get jerky or stuttery playback in every mode except MP4. if i use 4 k and dual record the mp4 is smooth but the 4k is very jerky no matter how slowly I pan or move.
even the auto zoom (digital zoom) is smooth on the MP4 but jerky on the 4K.
I have tried various shutter speeds from 1/50 to 1/200 but and lower as well but it seems the same. Any Ideas what I am doing wrong ?
 

Hawkman

TalkEmount All-Pro
Joined
Sep 10, 2013
Messages
1,243
Location
Virginia, USA
Real Name
Steve
Quick question: what are you playing the footage back on? The camera or a PC/Mac? It is entirely possible that if it is a PC/Mac, the computer may not have the power to smoothly play back 4K footage. It takes a fairly new and fast CPU, graphics chip, and hard drive to handle 4K well.
 

roundball

TalkEmount Legend
Joined
Oct 8, 2013
Messages
5,029
Location
USA
Makes me want to ask for verification on a questios as well.
I get the impression my NEX7 defaults to a particular shutter speed regardless of what speed I might have it set on...
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #6
Probably to old but also maybe i need a steady cam or gimble


Processor
AMD Athlon(tm) II X2 250 Processor
Manufacturer
AMD
Speed
3.0 GHz
Number of Cores
2
CPU ID
178BFBFF00100F63
Family
10
Model
06
Stepping
3
Revision

Memory
RAM
16 GB
Video Card
Video Card
NVIDIA GeForce 210
Manufacturer
NVIDIA
Chipset
GeForce 210
Dedicated Memory
1.0 GB
Total Memory
4.0 GB
Pixel Shader Version
4.1
Vertex Shader Version
4.1
Hardware T & L
Yes
Vendor ID
10DE
Device
0A65
Plug and Play ID
VEN_10DE&DEV_0A65&SUBSYS_080A10DE&REV_A2
Driver Version
21.21.13.4201
Operating System
Operating System
Microsoft Windows 7 Home Premium Edition Service Pack 1 (build 7601), 64-bit
Service Pack
1
Size
64-bit
Edition
Home Premium
Version
6.1.7601
Locale
0809
BIOS
BIOS
Default System BIOS
Version
American Megatrends Inc. 080015
Manufacturer
American Megatrends Inc.
Date
08/16/32
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #8
this one shows ok Hydrophobic_Paddles_NTV-HIGH_RES_MOV.mp4
 

bdbits

Super Moderator
Joined
Sep 10, 2015
Messages
2,428
Real Name
Bob
OK, that would seem to eliminate your computer as the issue.

If it was me, I would next try a tripod on a very simple, probably static subject. If that is still 'jerky', I would think it is either a settings issue or maybe the card is too slow on write speed (just an idea). If the tripod is smooth, then maybe some kind of stabilization will be needed when shooting off tripod, as you mentioned.
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #10
thats what I thought ; I will try with a tripod tomorrow and reply, I looking at a steadycam which certainly can't hurt anyway. Thank for the help Bob.
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #11
well thats disappointing while the tripod pan is smoother the 4k one; compared to the mp4 basic one the 4k one is very jerky, both are ok on static subjects

I dont think I can post sample clips here
 

bdbits

Super Moderator
Joined
Sep 10, 2015
Messages
2,428
Real Name
Bob
Sorry to hear it. Must be something fixable causing it, as I've seen some very nice 4k video shot with Sony bodies. But I am already at the bleeding edge of my knowledge on the topic. :(
 

adwb

TalkEmount Regular
Joined
Sep 30, 2015
Messages
162
Location
Bristol UK
Real Name
Alistair
  • Thread Starter Thread Starter
  • #13
well it might be the individual player, on some editing software its jerky but others, and using Sony playmemories home you have a save option with smoothing which seems to fix it ?

its all bit weird and , while for still images there are a million photographers on forums who will help with videography it seems very hard to get advice.

I thank you you for your kind suggestions and help.

I down loaded a full video taken on a7r2 in 4k , it took 1/2 an hour but it looks as bad as mine till I smooth it so it's not me but my pc I suspect.
 

Joe461

New to TalkEmount
Joined
Mar 28, 2019
Messages
2
I'm new here, but just came across this and thought I would offer some info:

also for XAVCS there are the two choices of 25p 100M and 25p 60M

25 is the frame rate ? is that correct ?

and should be matched to double the shutter speed =1/100 is that correct?

100M and 60M is the bit rate and 100 M will give a smoother video is that correct?
As mentioned by others, 25p is the frame rate and 100M/60M are the bitrate options.
if that is then correct then why is there a choice?
Higher bitrate is higher quality. It also generates larger files. This choice is similar to the jpeg size options for still images. Many people don't need the higher bitrate, so they can save storage space by using the smaller option.

I note that on XAVC S HD there is the choice of 50p 25p and 100p all at 50M compared to the XAVCS which only offer 25p

So why is there a choice 3 frame rates avaialble for the XAVC S format?
4k video has much more resolution than HD video. More data, larger file sizes and more processing power needed. All this data is compressed on the fly and written to the storage card. The smaller size of HD video (vs 4k video) allows for more frame rate options.


The stuttering playback issue is almost certainly the result of the machine you use for playback. I would bet good money that the actual files are fine.

4k video requires a lot of processing power. Again, the video is compressed to take up less storage space. Compression also means your playback device has to uncompress everything in real-time for playback.

I'm on a Mac (almost 10 years old), with CPU about the same speed as yours. I also have more cores, a lot more RAM and a faster video card with more RAM. I get poor playback on 4k video "out of the camera."

When I bring it into my video editor I can re-encode the files to a format more optimized for my system. That gives me smooth playback for editing but also increases the file size tremendously. It's using a "less efficient" compression method which delivers better performance at the cost of file size.

There's always a tradeoff. Speed, Quality, Cost (storage space). You only get to pick two of the three. :)


Edited to add: For a 25p frame rate, the idea of a 1/50 shutter speed (2x frame rate) is to deliver motion blur. It is a little counter-intuitive based on still photography. In stills, you want sharp focus. The "film look" involves a motion blur inherent in a 24fps system. There's no rule that says you have to keep your frame rate low. If you want to pull stills from your video footage, you probably want a higher shutter speed. If you want to achieve that "film look" that everyone talks about, then the slower shutter speed is a place to start.

(oops... of course I mis-read the thread date as 2019 instead of 2017. Still hope the info can be useful to some.)
 
Last edited:

Latest posts

Top Bottom