The Canon Files

Over on my other blog, I've made a few posts giving a little background information as we go through the process of shooting a short interview-based documentary using a Canon 7D. For example:

First Canon 7D Test
Second Canon 7D Test
Working with the Canon 7D

Thursday the first interview session was completed, so I'm going to give some details on the technical specifics in case anyone finds that useful.

The 7D records H.264 format files onto memory cards and those files should be transcoded to a format that works better in your nonlinear editing software. The H.264 QuickTime files that come straight out of the camera can be imported into most editing packages, but don't seem to perform well unless transcoded to a format like Apple ProRes. This results in larger files, but the new files work well for the editing process.

The specifics for our shoot:

1. the session resulted in 5 gigabytes of files.

2. when these files were transcoded to ProRes, the total expanded to 14 gigabytes.

3. that means transcoding to ProRes format expanded them to about 3 times larger (in filesize).

4. one file, shot at 1920 by 1080 dimensions and 24 progressive frames per second, was 9 minutes long and resulted in a 3 gigabyte file. So, for an interview, we saw 3 minutes equal about 1 gigabyte of filesize (as an H.264 QuickTime).

So, our first rule-of-thumb estimation:

In camera, you might get about 3 minutes of shooting time for each gigabyte of storage.

After transcoding to ProRes, your files may blow up about 3 times larger.

So: 3 minutes a gigabyte in camera. 1 minute a gigabyte after the transcoding to ProRes.

Easy to remember. We'll see if that holds up through the next interviews.

Next time: transcoding time.