What's with this footage?

C

cam123

Active member
Hi Friends,

Took some videos while waiting for an oil change.
lpowell settings. Thanks lpowell, we appreciate all your contributions to the community. :)

Settings:
720p - 60fps, Shutter=50

I apologize for my unsteady hands. Change the youtube videos to 720p to see it better.

Video 1 - Take a look at the beginning of the video, also while cars are passing by
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I AGREE


Video 2 - Take a look at the beginning of the video, also while cars are passing by
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I AGREE
 
The mud in the wake of the moving cars in Video 2 looks like macroblock breakup. In this case the AVCHD codec is confronted with both highly detailed static scenery (background trees) and large moving objects. To handle the trees, it only needs to encode the random changes in the fine details of the slightly moving foliage. But for the cars, it must calculate motion vectors covering a large area of each frame, and use whatever bitrate it has left over to fill in the details. When it runs out of bits, you get murky rectangular blocks that only crudely approximate the shape of the car. When the AVCHD codec chokes on scenes like this, the MJPEG encoder is often a better choice.
 
lpowell, concering your excellent "40Mbps AVCHD High Reliability Patch" I've found that with 720p when using shutter speeds below the frame rate (like 1/40 and less with 50fps) some pretty weird mud shows up in the highest bitrate setting when image content changes dramatically between frames. Dropping quality down to the lowest bitrate, ie; the original for 720p removes the occurance of this artifact. Otherwise your patch works just perfect. 1080p is awesome now.


For a example please check the attached image where I'm doing a fast camera repositioning during a take whipping it pretty uncontrolled. It's almost like one can see the motion prediction points. Shot with 720p @ 50 fps (PAL) and 1/30 shutter.
 

Attachments

  • wierdmud1.jpg
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Martti, if you are shooting below 1/50-1/60 with lpowells settings in 720 the codec dies in the ass and drops down to 3Mbits way below standard, hence why you see mud so easily. If you shoot at 1/50-1/60 you will have the full 40Mbit to work with and no mud, well hopefully. It is not lpowells setting specifically just an anomaly in bitrate vs shutterspeed.

My personal tests show that this drop in bitrate for shutterspeeds lower than 1/50-1/60 occurs when bitrate is set higher than 35Mbit. I have now set my H setting to 32-34Mbit in case i need to shoot at 1/30.
 
Thanks Bros.
Just like Martti, I experienced that same macro blocking.
Good thing there is a solution to that. Next time I'll up my shutter to >= 60.

I'll also play with greater than 120 shutter for a great slowmo in twixtor.

lpowell, so there is no way to have the fast action setting in low bitrate while having the 720 60p still.
Like,
FHD - 1080 24p
HD - 720 60p
SH - 720 30p in low bitrate


Thanks again lpowell for this awesome settings. I wish there is a thread where
we can thank you more everytime we see a great footage we captured.
 
cam123 said:
...so there is no way to have the fast action setting in low bitrate while having the 720 60p still.
Like,
FHD - 1080 24p
HD - 720 60p
SH - 720 30p in low bitrate
Click to expand...
Sorry, there's no way to combine 720p60 and 720p30 AVCHD modes in a single patch.
 
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