The AVCHD codec is a very processor intensive codec. A lot of computers have problem displaying and editing 1080i video (resolution 1920 by 1080) video. When editing video its important to have fast and smooth playback. You can also apply and preview effects a lot faster when not working with AVCHD. In this article some options to convert AVCHD to DV to work with AVCHD in a more fluent way.
In all the examples I use AVCHD 1080i50 (PAL 25 fps) as the source material.
Convert to SD (Standard Definition) video (720 x 576)
If your end-product is a standard DVD, this is the way to go. Of course you’ll lose quality (less pixels) and you have to use more disk space (less compression).
The DV codec the most common codec for SD. Most video tools and encoders support this codec. Below the settings for MediaEncoder CS4.
You can also download the AVCHD transcoder from Panasonic (windows only) if you have a Panasonic camera. Make sure you keep the directory structure of your smartmedia card, since it doesn’t recognize single .MTS files.
Another alternative (Mac only) is to import your material (again keep the structure of your smartmedia card) in iMovie. It will convert it to video with the Apple Intermediate codec and a resolution of 960 by 540 pixels (slightly better then 720 x 576). Counterpart is that the Apple Intermediate Codec isn’t available for Windows, so you cannot play it back under Windows.
Convert to Motion JPEG format anamorphic (1440 x 1080)
If you want to keep the 1080i quality you can convert to the Motion JPEG A codec. Its a light intra frame compression format (DCT compression like the DV codec) and it supports HD resolution interlaced material. This codec is also used in some broadcast facilities to store HD content.
I chose for a pixel aspect ratio of 1.333 (HD anamorphic 1080) to keep the filesize down, and make playback more fluent. You can alter the quality to a higher value, but keep in mind that the datarate and the filesize get bigger really quick (so editing gets less fluent).
You could also use this codec for storing an project in high quality for archiving purposes, since its impossible to store HD edits in the AVCHD codec with CS4.
Offline editing, Proxy video
If you want to keep the original quality you could first edit with a lower quality movie (convert to an SD movie with one of the techniques mentioned before) and then replace that with the original HD version.
A workflow is explained here : Quickly Edit HD Video in Adobe Premiere Pro with Proxy Video