mbps - how does it effect the video/image?

[Jeff Anderson]

just wondering, because the hack/patch(whatever way you'd like to look at it) is going have the option of raising the mega-bits-per-second for the GH2.

Will this drastically change the image quality? Did it on the GH1?

does it add latitude to the image?(colorspace)

[Bruce Watson]

Originally Posted by Jeff Anderson

just wondering, because the hack/patch(whatever way you'd like to look at it) is going have the option of raising the mega-bits-per-second for the GH2.

Will this drastically change the image quality? Did it on the GH1?

does it add latitude to the image?(colorspace)

Define "drastically." The AVCHD codec is a long GOP codec. That means that it takes a reference frame, and then for the next few frames it records just the differences with the reference frame. The reference frame and the difference frames are then compressed using a lossy algorithm. And in the end it all comes out looking pretty darn good amazingly enough.

Where you'll see the benefits of a higher bit rate is where there's motion in the frame. For example, if you're filming a basketball game -- panning down the floor as the players run. Not enough bits will show as the checking in the wood floor turns to mush. It can also show as a player goes up for a shot as bigger pixels along the players arms as they move -- this is called macro-blocking.

But bit rate has nothing to do with the color space of the image (typically REC.709 for HD), and the color space defines the gamut available to the image. Similarly, the bit rate has nothing to do with the hardware's sensitivity (sensor well size/depth) and therefore can not effect properties such as dynamic range.

So what you'll typically get from a higher bit rate (besides bragging rights) is an already pretty good picture will be somewhat cleaner, and motion artifacts will be reduced. If the camera itself is in motion a lot, this might indeed be "drastic". If you're filming a locked down talking head interview, probably not so much.