Inspired by : http://www.elementaltechnologies.com/blog/primer-inter-vs-intra-frame-video-compression
What is the best picture codec for use in Pro Tools?
Many picture houses try to supply us with H.264 codec as this ‘looks great’ and has small file sizes. While this might be true, working with it in Pro Tools becomes a nightmare. Scrubbing fails to operate smoothly, moving round the timeline is positively glacial and altogether it’s more hassle than it’s worth.
As stated in the above blog post Intra frame images are single snapshots of each frame of the movie. This means that for each second of picture there will be 24 frames of video (assuming a 24frame project, replace this figure with 29.97, 30, 25, 23.976 as appropriate).
Why is this good?
This is good because the computer only has to process that frame. It doesn’t need to think about frame 10 if it’s on frame 23 meaning that scrubbing, timeline jumping… everything about the operation of the DAW is smoother.
The various QuickTime codecs that are available at this point become reasonably similar, certainly in terms of processing requirements.
As a company we have tended to stick with DV based codecs for the vast majority of our projects. As stated in a previous entry we use MPEG Streamclip for converting the picture if a picture department refuse/are not able to produce a DV codec for us. The most common codec thast we have been using recently is the DVC PRO NTSC. This is a DV based NTSC (29.97) codec that is well suited for the 23.976 workflows that have been prolific over the past few years.
In the US they tend to work with Photo JPEG files. These have a higher picture clarity due to each frame being a JPEG image of the video footage. There is a trade off here with file size. a DVC file of 20 minutes comes to around 1.6GiB while a PhotoJPEG comes in at more like 2.8GiB. It’s not a massive difference but it adds up over the course of reels and 15-20 versions (excluding VFX updates).
What else is there?
In October of 2009 Avid released a new codec for QuickTime that has yielded some impressive results in testing. It’s called the Avid DNXHD Codec for QuickTime and it is wonderful. In my opinion it looks much better than the H.264 equivalent and it has NO additional overhead to a system.
A standard photo JPEG/DVC Pro QuickTime requires 8-10% of a CPU to playback within Pro Tools. The Avid DNXHD codec for QuickTime plays back with maximum (in testing) 8% CPU usage.
For the next show that we do I’m going to try to specify this as our preferred option as it is closer to the playback specification for the stage. It’s only downside is that files are larger. 20 minute reel will be in the region of 4.5GiB. I figure we’l just keep fewer versions ;)