What is resolution of stabilized video clip?

Rich Parry wrote on 9/5/2014, 11:24 AM
I believe the following is true.

After a video clip is stabilized, the video resolution is reduced. For example, if you start with a 1920x1080 clip, after stabilization, the resolution might be 1800x1000. The exact resulting resolution is a function of how much stabilization was required and will vary from clip to clip.

QUESTION: Does VP13 show somewhere the resolution of the stabilized clip?

Rich in San Diego

Comments

OldSmoke wrote on 9/5/2014, 12:03 PM
No, the resolution has not changed; what happens is similar to a Pan/Crop.

Proud owner of Sony Vegas Pro 7, 8, 9, 10, 11, 12 & 13 and now Magix VP15&16.

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Laurence wrote on 9/5/2014, 12:06 PM
This would vary with how much you need to zoom in to cover the borders. There is no single exact answer to this.
musicvid10 wrote on 9/5/2014, 1:29 PM
The cropped image is scaled to fill the output resolution.
Usually this means an indeterminate amount of upscaling.
Some stabilizers attempt to get around this by edge interpolation.
johnmeyer wrote on 9/5/2014, 2:55 PM
Boy, you sure are getting a lot of answers that parse semantics, and therefore dance around the issue.

Your basic question is how much does Mercalli degrade the resolution of the clip, and is there a way to measure this degradation? The answer is that the clip is definitely degraded, and its resolution is quite definitely reduced, but no, Mercalli does not provide any feedback on how much resolution is thrown away.

I was not able to figure out a simple way to measure the resolution degradation, other than put a duplicate event on the track above, and then manually adjust its pan/crop until its size matches the stabilized clip. You can then read the clip's resolution from the pan/crop box.

The other answers above are misleadingly correct: the stabilized clip is ultimately scaled back up to the original resolution of the clip, so the resolution appears to be unchanged, and therefore it is correct to say that the ultimate resolution is unchanged. However, this is very misleading because before that scaling operation is performed, Mercalli zooms into the clip in order to cover up the black borders created by the stabilization operation. At that moment, before up-scaling, there are fewer pixels in the clip than there were in the original, unstabilized clip.

Its resolution has been changed!

This resolution reduction can result in significant degradation of the image because, even though the image is scaled back up to the original clip's resolution, the underlying number of pixels has been diminished.

With the purchased standalone version of Mercalli you have more controls, but I don't think that version provides information on the exact amount of zooming done on any given clip. Perhaps someone who owns the standalone can chime in.

If you have the purchased plugin version of Mercalli (I own this), it provides far more controls than the significantly de-featured version that ships with Vegas. In particular, it gives you more ways to deal with the border issue, including not zooming. If you choose this, your clip's resolution is not degraded, although it is true that the clip will still have to be re-sampled in order to move and rotate the image in order to achieve the desired stabilization, so there will be some degradation in quality from this, although this is trivial by comparison to the lost resolution quality hit.

So, in summary, if quality is your goal, then get the version of Mercalli that lets you correct the borders without zooming. Alternatively, try the free Deshaker program which also has a border correcting feature. I think Mercalli is a better overall stabilization program, but for many of my clips, I find that the border fill with Deshaker is better.

GlennChan wrote on 9/5/2014, 3:43 PM
Assume that the image is rescaled. The new resolution depends on:
A- How you want to measure resolution.
B- What algorithm was used to rescale the image.

When you rescale the image, you will run into the following problems:
1- Loss of resolution.
2- Aliasing.
3- "Ringing" artifacts.

You can see pictures of that here:
http://www.glennchan.info/broadcast-monitors/scaling-artifacts/scaling-artifacts.htm

If you optimize for one of those problems, you will suffer somewhere else. Some algorithms do a good job at keeping resolution, but there's always a drawback. Usually ringing artifacts are the least awful.

---
In practice, learn how to spot the artifacts:
blurriness / new image doesn't appear sharp
aliasing on fine lines, certain fabrics, etc.
ringing artifacts - halos around edges.

Usually you can rescale without having problematic artifacts. But if you run into artifacts, there are some tweaks you can do to get rid of them (or to reduce them).
GlennChan wrote on 9/5/2014, 3:45 PM
You could apply fancy mathematics or simple mathematics to try to measure the loss in resolution.

In practice, I don't think that it would be useful to do that.
Rich Parry wrote on 9/5/2014, 4:12 PM
John,

You are absolutely correct, your response was exactly what I was trying to ask. I'm trying to measure "degradation" or "loss of resolution" from the stabilization process. I want to objectively measure stabilization changes so I can experiment with various stabilization settings. Your response tells me there is no easy way of knowing how many pixels are discarded.

I should mention I've been using the Sony built-in stabilization tool, not Mercalli, I thought Sony did a pretty good job, but after sending this post I'll look into Mercalli.

Thanks to all that replied,
Rich
johnmeyer wrote on 9/5/2014, 4:41 PM
[I]I should mention I've been using the Sony built-in stabilization tool, not Mercalli,[/I]Isn't the Sony built-in stabilization tool OEM'd from ProDad (the company that develops Mercalli)?
NormanPCN wrote on 9/5/2014, 4:43 PM
I have Mercalli stand alone, V3, and it does tell you the zoom/crop percentage. For example 108%. With Sony I just click the effect on/off to gauge how much crop/zoom is going on.

The Sony stabilizer is Mercalli V2 underneath but we get little control or information from the plug-in. Be careful with the Sony stabilizer. Read the help on the control settings. They are very poorly named. The "stabilization amount" is actually the tilt and zoom stabilization. The "pan smoothing" is the Mercalli "pan shot smoothing", up/down/left/right, which is the main stabilization parameter according to proDad.

I posted a thread on these quirks a while back.
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=888701
johnmeyer wrote on 9/5/2014, 8:09 PM
I have Mercalli stand alone, V3, and it does tell you the zoom/crop percentage. For example 108%. With Sony I just click the effect on/off to gauge how much crop/zoom is going on.Thank you very much for that reply. I suspected from the Mercalli plugin help file -- which includes help for the standalone version -- that this might be the case. It is another reason why I someday may purchase the standalone in addition to the plugin.
riredale wrote on 9/5/2014, 8:23 PM
I should mention, by way of comparison, that the other stabilizer used here is the free DeShaker. When combined with the script, it's really trivial to use and offers a host of adjustments.

One result you can select is to not have the output zoomed at all. Instead, DeShaker will automatically look ahead and look behind a certain number of frames to see if it can fill in the black area with something that closely matches. In most cases, this works suprisingly well. So in this instance there is no loss of resolution due to zoom.

However, the guy who wrote DeShaker says in his detailed description that there is a loss of vertical resolution due to interlace, if that's the source.
John222 wrote on 9/5/2014, 9:29 PM
How about when using Mocha Pro to stabilize with the fill option. Any down sides?
PeterDuke wrote on 9/5/2014, 9:29 PM
It also depends on how fine the stabilisation attempts to be.

Assuming the video is progressive, it might realign a frame to the nearest pixel, leaving a small jitter, but no further loss of sharpness beyond the rescaling. For better smoothing, it would interpolate between pixels so that the frame could be shifted a fraction of a pixel if necessary. This would lead to further loss of sharpness.

If the video is interlaced, then this would be carried out on each field rather than frame, and vertical interpolation would have to span two lines rather than one.
Rich Parry wrote on 9/6/2014, 11:59 AM
After a little Mercalli research, it appears that only Mercalli V3 Stand alone version ($179) supports 4K. I believe stand alone means that after stabilization you have the original file and new stabilized file, so now I have 2 large files, not sure when it is safe to delete the original.

I don't really have a question, I'm just overwhelmed with the workflow of stabilization, proxies, and codecs. I guess this is a learning opportunity. My head is hurting.

Rich
NormanPCN wrote on 9/6/2014, 12:51 PM
You can get Mercalli V3 SAL for less than 179. Amazon and B&H Photo both sell it less than $149 USD.

I believe stand alone means that after stabilization you have the original file and new stabilized file

Yes, this is correct. For me, I like to get the stabilization out of the edit loop. Stabilizing on the fly is overhead that might make edit playback, less than perfectly smooth.
Rich Parry wrote on 9/6/2014, 2:39 PM
Norman,

I am a still photographer that recently joined the video and 4K revolution and don't have a video yet. So may I bother you a little more.

Sounds like stabilization is the first thing you do with a clip, right?

Is there an output codec you like to use in Mercalli V3 SAL before putting on a Vegas timeline?

Do you eventually delete the original video files when your project is done?

Rich
Mark_e wrote on 9/6/2014, 2:54 PM
I've been playing working out 4k workflow that I like

For general stabalization I'm using deshaker with 4k and virtual dub for free just get 64bit versions of each.
Deshaker looks daunting but it's not once you get your head around it and seems to work as well as or better than commercial stuff I've tried.
For 4k I brought the Morgan m jpeg2000 codec it's not a lot of money and you can make nice lossless upto 4:4:4 files in an an avi wrapper all multi threaded etc. and plays nice with vegas and virtual dub.

I usually stabalise before editing and when I shoot in 4k if I know I am going to want to stabalise in post I try and frame it with some room to spare so I can have some black boarders showing and crop then resize to 2k or 1080p with no real quality loss.

For more creative stabalization mocha gives different more creative control but more time consuming specials only :)
NormanPCN wrote on 9/6/2014, 3:48 PM
I am a still photographer that recently joined the video and 4K revolution

I am quite new to video as well, though I doubt I will ever care about 4K. I came over from the Photography Photoshop world also.

Yes, I stabilize first. Mercalli V3 only supports one output codec type. That being AVC using the x264 encoder. I use the Medium (default) setting mostly and High output setting at times. High, when if then send the Mercalli output into proDad Respeedr for SlowMo.

I keep both the original and the stabilized media, although I am not sure what I would ever do with the original once done with a project. HD space is not a problem for me and I don't have a lot of video anyway.

4K would certainly change the file size situation a bunch. My media are 35Mbps GoPro files. The Mercalli output file size varies considerably depending on how well something compresses. Cameras just don't have the compute power or the time to compress as well as PC encoders.

I have suggested to proDad that they change their 3 output options to 5. Thus giving users more options to get a bitrate suitable for their specific camera output bitrate. I have also suggested they add a "fast Decode" check box to turn off CABAC encoding, which will give faster decoding on a users NLE.
johnmeyer wrote on 9/6/2014, 4:55 PM
Sounds like stabilization is the first thing you do with a clip, right?No, not usually. In fact, many on this forum will tell you that you should never stabilize a clip because you should use a tripod and therefore don't need to do stabilization. Of course those of us who do certain types of event videography that doesn't allow time to set up a shot, must shoot handheld, and sometimes that footage needs help. Even clips which contain some camera movement do not necessarily need to be stabilized.

Less is more.


Is there an output codec you like to use in Mercalli V3 SAL before putting on a Vegas timeline?I realize that your question is about the standalone version but, in case you didn't know, if you purchase the plugin version (which is what I use), then you do not need to create any intermediate clips and don't need to render (until you render the entire project).

Do you eventually delete the original video files when your project is done? Speaking for myself, I never delete any original files, under any circumstance. You can always re-create your stabilization, if need be, but you can never go back to the original files. If the standalone Mercalli lets you save project files, you can save those, and then easily re-do the stabilization.
NormanPCN wrote on 9/6/2014, 6:46 PM
In the GoPro world software stabilization is very nice to have. My mountain bike is anything but stable.