Transcoding Fun

I just installed Toast 10 and tested to see how long it takes to convert AVCHD to DVCPRO HD. The answer is about real time, or a little over 8 minutes for 8 minutes of footage. The file size was surprising - a :17 clip was 148.9 MB in ProRes, while the same clip in DVCPRO HD ballooned to over 236.2 mb.

At first glance in Quicktime Pro, there was substantial difference in color between the two as well:

In this screen grab you'll see the same frame with the QT window in the background being ProRes and the foreground being DVCPRO HD. There is noticeably less color in the DVCPRO HD. But when you export still frames from each of these clips, something surprising (to me) occurs:

The JPEG above shows the two clips merged together. On the left is DVCPRO HD, and on the right is ProRes. There's no noticeable difference to me other than the frame size diffence which shows the most in the lower center of the image where the trustle's support structure doesn't quite line up. In Final Cut Pro you also do not see a noticeable difference. The scopes do reflect a minor change when you toggle between them.

So I'm puzzled as to why these codecs look so different in QuickTime and yet look almost identical when used inside FCP. Ignoring the file size difference for a moment, DVCPRO HD seems like a possible winner. My assumption is it would be less tasking on my system than ProRes 422, however I cannot ignore the file size difference. For whatever reason DVCPRO HD comes out as the bigger file when using Toast 10 to export.

Perhaps I'm missing something here?

ProRes 422

So you have two options when you transcode AVCHD in Final Cut Pro's Log and Transfer - convert it to AIC (Apple Intermediate) or ProRes 422 (and not of the HQ variety). I chose ProRes. So how big do the files get after transcode? About 5 times as big! So it looks like for every 16 GB card you shoot, you're looking at close to 80 GB in ProRes QTs on your drives. Ouch. Thankfully my system - a Mac Pro Quad 3 - can chunk through these files in about 50% realtime (i.e. - 8 minutes of footage takes about 4 minutes to transcode. That beats digitizing!)

I want to experiment with transcoding to DVCPRO HD next. It looks like I'll have to use Toast to do this. Thankfully Toast 10 came from Amazon today!