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View Full Version : Olympics diving camera "oddity"



R.A.F.
2012-Aug-12, 09:29 PM
So I've been watching diving...in particular, platform diving, and noticed something "unusual".


With each and every dive, the video "pixelates" when the diver is about two thirds of the "way" down.


...and this happens on every "live" dive....doesn't happen in replays



Am I the only one who has noticed this?....and what could the explanation be??

Moose
2012-Aug-12, 10:08 PM
If it's a repeating issue, then it sounds algorithmic.

Wild guesses:
1) An auto-focus problem at that angle with that camera. It might be trying to focus on something other than the diver for that moment.
2) The camera having trouble dealing with a problematic light reflection.

slang
2012-Aug-12, 10:16 PM
Am I the only one who has noticed this?

You might be the only one watching... ;)

R.A.F.
2012-Aug-12, 10:21 PM
If it's a repeating issue, then it sounds algorithmic.

The first half dozen times, I tried to convince myselt that I was imagining it. Then I started counting, and it got real agravating, real quick...

The agravation "factor" reminded me of the lens flares in the Star Trek reboot.




Wild guesses:
1) An auto-focus problem at that angle with that camera. It might be trying to focus on something other than the diver for that moment.
2) The camera having trouble dealing with a problematic light reflection.

You might have something with (1). It always happened at the exact same angle.

I didn't notice any reflections that might have caused "problems".

HenrikOlsen
2012-Aug-13, 07:37 AM
Could be that's when the camera is turning fastest, so the interpolation/extrapolation prediction algorithm's getting messed up because too much of the screen is changing for the bandwidth to handle because there's too not enough similarity between subsequent frames.

Moose
2012-Aug-13, 11:11 AM
I like Henrik's idea. Better than either of mine.

grapes
2012-Aug-13, 12:16 PM
Didn't the diving camera drop alongside each dive, rather than turn? Still, it may have not "caught up" in real time, but the post-processing could be smooth. You'd think they'd have noticed.

Paul Beardsley
2012-Aug-13, 12:20 PM
Could be that's when the camera is turning fastest, so the interpolation/extrapolation prediction algorithm's getting messed up because too much of the screen is changing for the bandwidth to handle because there's too not enough similarity between subsequent frames.

Having worked in video, I favour this explanation.

R.A.F.
2012-Aug-13, 12:25 PM
Didn't the diving camera drop alongside each dive, rather than turn?

That's one of the replays. This only happened in the live shot, filmed from the right hand side.



Still, it may have not "caught up" in real time, but the post-processing could be smooth. You'd think they'd have noticed.

It's a bit subtle unless you are looking for it, and it only lasted, maybe, a quarter of a second.




I like Henrik's idea. Better than either of mine.

Yes, but can you say it 3 times fast? :)



I'll see if I can find a linkable example....(should have done that, yesterday.)

edit to add....should have expected.....the online video is clean as a whistle...unless someone has a "broadcast" example (which I DID, until I erased it) then this looks like the end of the road for this "investigation".

Darn it.

grapes
2012-Aug-13, 01:24 PM
That's one of the replays. This only happened in the live shot, filmed from the right hand side.
I'm confused by what is live, and what is replay.


It's a bit subtle unless you are looking for it, and it only lasted, maybe, a quarter of a second.
That *would* be subtle, nice catch.


I'll see if I can find a linkable example....(should have done that, yesterday.)

edit to add....should have expected.....the online video is clean as a whistle...unless someone has a "broadcast" example (which I DID, until I erased it) then this looks like the end of the road for this "investigation".

Darn it.At least, you can rule out your own equipment, as a source. :)

DonM435
2012-Aug-13, 02:49 PM
I'll bet it's something in NBC's cameras or transmission lines.

The past couple of years I've tried to watch the National Hockey League playoffs on their "Versus" channel, and both years there was intermittant but frequent pixellation in the live action that didn't show up in replays. Also, it didn't seem to affect regular programming on that channel (which I admit, I rarely watched -- lots of wrestling and fishing shows and probably fish wrestling for all I know.)

Even if you could overlook the patchy video, the audio would fracture, sounding as if the announcer had just developed a brogue while getting electrocuted. That was really maddening.

I fought with my local cable company over this, but maybe it wasn't their fault.

R.A.F.
2012-Aug-13, 03:05 PM
I'm confused by what is live, and what is replay.


Ok...so the diving event comes on. First diver up....takes his dive...the video of that dive.

All video after that....showing that dive, are "replays".



That *would* be subtle, nice catch.

Too bad my Wife didn't think so. (It might have had something to do with my repeated "did you see that?....did you see that?")



At least, you can rule out your own equipment, as a source. :)

Just wish I had saved an "example". I "kinda" feel like the boy who cried wolf...I can't show that this actually happened, but I know it did.


I was hoping I wasn't alone in noticing it.

slang
2012-Aug-13, 05:25 PM
I can't show that this actually happened, but I know it did.

I was hoping I wasn't alone in noticing it.

I can't say I noticed it in diving, then again, I didn't watch any. But I've seen similar things quite often during soccer games on TV, especially when digital formats began being used. It reminded me of pictures being JPG compressed too much, maybe it was some available bandwidth issue.

R.A.F.
2012-Aug-13, 06:06 PM
...I've seen similar things quite often during soccer games on TV...

As have I...


The interesting "thing" about this, is that it occurred in the same spot of the dive, (about 1/2 to 3/4's of the way down), and it happened on every "live" dive.

grapes
2012-Aug-13, 07:14 PM
Ok...so the diving event comes on. First diver up....takes his dive...the video of that dive.

All video after that....showing that dive, are "replays".
Yes, that would be a replay. :)

However, you're talking about *saving* the evidence, which would also be a *replay*.

It appears that you are blaming this on a specific camera, maybe? That all copies made with that "live" camera will show this glitch? Or, it could be, that every camera that transmitted during the live dive showed the glitch--but if they didn't transmit but only recorded, then they didn't have the glitch?

SeanF
2012-Aug-13, 08:10 PM
Yes, that would be a replay. :)

However, you're talking about *saving* the evidence, which would also be a *replay*.

It appears that you are blaming this on a specific camera, maybe? That all copies made with that "live" camera will show this glitch? Or, it could be, that every camera that transmitted during the live dive showed the glitch--but if they didn't transmit but only recorded, then they didn't have the glitch?
Probably, yes. The system records at a greater bandwidth than what can be transmitted over the airwaves. When the system is transmitting the dive "live," it must compress each frame without knowing what the next frame is going to be. When transmitting the replay, it can "read ahead" and compress multiple frames together. It's not unreasonable that it gets better compression when doing the latter than when doing the former.

That's my theory, anyway. ::smile::

R.A.F.
2012-Aug-13, 08:53 PM
....you're talking about *saving* the evidence, which would also be a *replay*.

Not if it was recorded "as it happened".

edit to add....which now that I think about, doesn't make any sense...it was all tape delayed, so why would it not appear on ALL replays?



It appears that you are blaming this on a specific camera, maybe? That all copies made with that "live" camera will show this glitch? Or, it could be, that every camera that transmitted during the live dive showed the glitch--but if they didn't transmit but only recorded, then they didn't have the glitch?


When watched live, the "glitch" was there...yet when I "found" it, today on the net, the "glitch" was gone.


....and I don't have a clue as to what it was...

SeanF
2012-Aug-13, 09:43 PM
R.A.F., did you see my post? I think that's probably what was going on.

Where did you find it on the net? Was it from the official Olympics website, or something somebody uploaded to YouTube?

R.A.F.
2012-Aug-13, 09:51 PM
DOH!....yeah, I see your post, now....should have seen it before...


It was from the Olympics/NBC site.

SeanF
2012-Aug-13, 09:55 PM
It was from the Olympics/NBC site.
Okay, so it's a recompress from the original recording, rather than a recording of the original broadcast, so no pixelation (or, at least, different, less noticeable pixelation).

I'm no digital video expert, by the way, but this all seems to make sense to me. ::smile::

publiusr
2012-Aug-13, 10:21 PM
Could the camera be feeling water pressure spike--which Of course--isn't there in replays? I seem to remember some talk about scintillation when pulling back scotch tape. I seem to notice the same effect when a lot of action. On the last series of the new Full Metal Alchemist, the opening scene showing Pride is quite choppy. That's more of the case with a refresh rate you were speaking of. Sort of like the whine you hear after explosions in a digital format--or halos of different darkness.

I wonder if the camera is being influenced by impact in some way.

SeanF
2012-Aug-14, 01:18 PM
Could the camera be feeling water pressure spike--which Of course--isn't there in replays? I seem to remember some talk about scintillation when pulling back scotch tape. I seem to notice the same effect when a lot of action. On the last series of the new Full Metal Alchemist, the opening scene showing Pride is quite choppy. That's more of the case with a refresh rate you were speaking of. Sort of like the whine you hear after explosions in a digital format--or halos of different darkness.

I wonder if the camera is being influenced by impact in some way.
I only see a couple problems with that theory - first, the OP suggests that the anomaly occurred before the diver hit the water, so it couldn't be the impact which "shocked" the camera.

Secondly, it would require that the shock affects what the camera transmits, but not what it records.

And now that I think about it, it would also require that the replays actually originate from the camera itself rather than from a recording in the control booth...

R.A.F.
2012-Aug-14, 06:44 PM
...the OP suggests that the anomaly occurred before the diver hit the water, so it couldn't be the impact which "shocked" the camera.

I didn't think I was "suggesting" it, I thought I had actually said it. :)


Anyway...it happened when the divier was about 3/4 of the way down to the water.


...and I've watched a few of the diving replays, and I think Moose may have it right about it being a light reflection, as the diver passes past a very strong light source as he dives.

...for some reason, this is the first I've noticed that...

SeanF
2012-Aug-14, 08:24 PM
I didn't think I was "suggesting" it, I thought I had actually said it. :)
Hey, a smiley! They work now! :D


...and I've watched a few of the diving replays, and I think Moose may have it right about it being a light reflection, as the diver passes past a very strong light source as he dives.
Any chance of a link to a particular video and a reference time for when you remember seeing the glitch?