Canon C100 vs. Sony FS700

[Tom Roper]

Originally Posted by David heath

I'm quite prepared to accept that at lower bitrates software encoders (non-real time) for H264 may well require less than half the datarate of MPEG2 for equivalent quality. At higher bitrates (>25Mbs), and for realtime camera encoders the difference will not be anything like as great as 2x.

Which brings it round in a circle. A new AVC-HD spec of around 40Mbs may indeed rival XDCAM422 for quality - but is it worth it? Is the datarate drop of about 20% worth the complexity?

I agree with all your points. Is it worth it, and I think you mean 35 Mbps AVCHD? No, I do not think it is. (But I still like the h.264 codec for final renders, and I don't regard working with AVCHD from cams as presenting any particular problems.) But my preference for a shooting format remains XDCAM 422 50-100 Mbps.

[Chris Medico]

Originally Posted by David Heath

And a key point is the difference between real time and non-real time encoders. If you're compressing within an NLE in a powerful computer it's obviously more feasible to use all the possible "tricks" - it'll just take longer to encode!

But a camera has to do it in real time, and is very unlikely to have the processing power of even a moderate computer. Hence the encoding tends to be much simpler.

David, I hope you don't mind me repeating from you the most important thing that anyone discussing AVCHD compression needs to understand.

There are lots of methods that can be used with AVCHD to increase the compression ratio of the video while maintaining great quality. They require the video to be analyzed in larger and larger chunks. That takes a ton of memory and processor power. Cameras just can't do it in real time. Some of the "tricks" they can use improves things in comparison to MPEG2. Maybe 20-25% smaller. Thats about it.

One thing for sure my computer would much rather edit MPEG2 versus AVCHD. In edit performance alone I have no problem giving in to the larger storage footprint of MPEG2.