A Bit Rate Test to Try

adamr316

adamr316

Well-known member
I was just thinking...

In S&Q motion mode, the bitrate tends to be a little higher than 35 MB/s, right? So what if you record at 24p?

I notice audio still works at 24p...but does the video bitrate get higher in that mode "just because"?
 
After some testing it looks like putting the camera into S&Q motion at 1080/24p doesn't give a higher bitrate. Maybe 720/24p will?
 
Maybe Barry or someone can correct me if I'm wrong, but my understanding is that the camera always records at 35Mbps.

The question then is; if you shoot at 24fps instead of 30 fps and both record at 35Mbps, isn't the 24fps less compressed?
 
Duke M. said:
Maybe Barry or someone can correct me if I'm wrong, but my understanding is that the camera always records at 35Mbps.

The question then is; if you shoot at 24fps instead of 30 fps and both record at 35Mbps, isn't the 24fps less compressed?
Click to expand...

I think it does shoot at a higher bitrate in S&Q, but maybe that is just for the extreme range (say, 48fps and above?). The higher bitrate is the reason memory cards couldn't handle overcranking...I think.

And yes, 1080/30p is more compressed than 24p. 20% more so I would assume (80% of 30 is 24).
 
When you're *not* in S&Q mode, it's always 35mbps (well, of course assuming that you're shooting the HQ mode). Whether you're shooting 1080/24, 1080/60i, 720/60p or 720/24p, doesn't matter, it's all 35mbps.

But when you put it in S&Q, and juice the frame rate up, then it can take up quite a bit more of space. Implying that each frame is being compressed less. So if you compare 720/60p against 720/24p in S&Q @ 60fps, yes the S&Q footage should take up a lot more space on the card, and be more lightly compressed, than the straight 720/60p footage was.
 
Barry_Green said:
When you're *not* in S&Q mode, it's always 35mbps (well, of course assuming that you're shooting the HQ mode). Whether you're shooting 1080/24, 1080/60i, 720/60p or 720/24p, doesn't matter, it's all 35mbps.

But when you put it in S&Q, and juice the frame rate up, then it can take up quite a bit more of space. Implying that each frame is being compressed less. So if you compare 720/60p against 720/24p in S&Q @ 60fps, yes the S&Q footage should take up a lot more space on the card, and be more lightly compressed, than the straight 720/60p footage was.
Click to expand...

Ah. I found this too.

"For example 24/60 (overcrank) will play back slow mo at 35mbps VBR in your base frame rate. Shooting at p60 is already at 35mbps VBR so slowing that done gives you less data per frame. Don't forget you have to "conform" that p60 to whatever your base frame rate will be in post too.

In other words, overcrank is actually recording x/60 at something like 70-87.5mbps VBR. That's one reason why SxS cards are more expensive than others because they need to sustain that record rate plus headroom."
 
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