We (Canon DSLR video shooters) have all been using MPEGStreamclip for our footage conversion, from H.264 to Apple ProRes. Not bad result and good speed all around. But since a few months another tool is available that i have been testing for a while, that delivers slightly better results with the YCbCr to RGB conversion: 5dtorgb. I was preparing a post on the whole subject with examples, but found a few links to blogs and videos from people who did just that the previous month(s). And the results are promising!
Here is a short blogroll (not a rickroll… remember that..?!):
- Robin Schmidt’s blog with testvideos and measurements
- Motion Life media blog by Jerome Stern, who specifically focusses on the subject of Gamma
- 16×9 cinema article with good examples and discussion
- the 5DTORGB website
From the links above you can follow many other links to tests and discussions.
For my tests, i’ll stick to using the latest version of 5D2RGB, but i will definitively remain using MPEGStreamClip for all the other (non-H.264) conversion jobs around the house….
From the 5d2rgb author’s website at http://rarevision.com/5dtorgb/
5DtoRGB is an awesome tool that extracts every last drop of video quality from cameras that record to the AVC/H.264 video format. Cameras like the Canon EOS series of HDSLRs record video in this format with subsampled YCbCr color. Because of this compression, the video is at risk of massive quality loss during the post production pipeline. By using a very high quality conversion process, 5DtoRGB gets you as close as possible to the original data off the camera’s sensor while putting the brakes on any additional quality loss. In short, it’ll make your footage look just plain amazing!
5DtoRGB is designed to transcode your footage to a camera master format, either as Apple ProRes QuickTime files or DPX files. This master format is a much higher quality version of the original footage off the CompactFlash card, and is suitable for editing or visual effects purposes. Transcoding to DPX is useful for visual effects creation (like pulling mattes from green screen footage), as DPX files are uncompressed and retain the most image quality. Furthermore, visual effects compositing programs like After Effects or Nuke work with RGB color (not YCbCr, which is the camera’s native format), and so a YCbCr to RGB conversion must be performed by either QuickTime or your compositing program before anything useful can be done.
The main problem with all this is that you have to trust your NLE or compositing app to do a good job of performing the YCbCr to RGB conversion. Many programs use QuickTime internally to perform YCbCr to RGB conversion which, according to our testing, does only a mediocre job. I suspect this due to a performance compromise, in that “well enough” is suitable for most users (remember, QuickTime is designed for real time playback of those 1080p movie trailers as well). This is probably OK for general use, but unacceptable when trying to maximize the quality of highly compressed H.264 footage for visual effects work, green screen compositing or film outs. To add insult to injury, QuickTime adds noise to its H.264 output (and so does any program that uses QuickTime to decompress H.264) in what looks like an attempt to cover up H.264 compression artifacts. And guess what? There’s no way to disable this. You’re stuck with it if you’ve converted your footage with Final Cut Pro, Adobe After Effects, MPEG Streamclip or Canon’s Movie Plugin-E1 for Final Cut Pro — all of them use QuickTime to decompress H.264. For an example of the result of this is, click here.
5DtoRGB takes a no-compromise approach to quality, ignoring any concerns about speed. 5DtoRGB bypasses QuickTime decoding altogether, works internally at 10 bits and uses double-precision floating point math for its YCbCr to RGB conversion. It also recognizes Canon’s full range 8 bit YCbCr values (0-255), avoiding clipping and the resulting loss of picture information. The resulting files are the absolute highest quality you’ll ever get out of the camera. In fact, you could argue that they’re even better than the camera originals since they’ve undergone high quality chroma smoothing (which you can disable if you want, but you shouldn’t).
5DtoRGB gives users the power to overcome the incredibly annoying gamma issues that have plagued Final Cut Pro and QuickTime users for years by allowing complete control over gamma correction and flagging.
5DtoRGB includes timecode support. Start timecode values are derived from THM files, just like with Canon’s official E1 plugin for Final Cut Pro and inserted into the DPX files or ProRes QuickTime files. You can also specify your own timecode value if you want.
5DtoRGB runs right now on Mac OS X, with Windows and Linux GUI versions planned.