ProRes Proxy @ 36 mb/s vs. AVCHD @ 24 mb/s

[EJ Horstman]

I was shocked to discover that recording ProRes Proxy via Pix 240i resulted in much poorer quality images than the internal recording AVCHD. Take a look at the blocking and color compression, especially in the woman's face on the right. I realize Proxy is just an editing codec, but I figured the higher bit rate would mean better quality. Thoughts?

 

[cuervo]

When comparing different codec compression methods, bitrate is NOT a relevant parameter to use for comparison. Different compression schema have different compression efficiencies. AVCHD is a highly efficient codec that maintains quality much better than the old MPEG2, for example. The downside is that AVCHD is much more processor intensive and requires a much faster CPU to decode it than MPEG2, which is why many older computers can't playback AVCHD without dropping frames.

 

[EJ Horstman]

When comparing different codec compression methods, bitrate is NOT a relevant parameter to use for comparison. Different compression schema have different compression efficiencies. AVCHD is a highly efficient codec that maintains quality much better than the old MPEG2, for example. The downside is that AVCHD is much more processor intensive and requires a much faster CPU to decode it than MPEG2, which is why many older computers can't playback AVCHD without dropping frames.

Very good to know, thank you!

 

[nyvz]

Prores is intraframw only, avchd uses intraframe and interframe temporal compression which allows it to appear much more efficient for motion images, though it may performs worse in a select few areas (for example imagery containing random noise).