Questions on Transcoding Video
[ This article was first published in the September, 2010, issue of
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Randy Holman asks:
In one of your tutorials you indicated ProRes422 only worked with 23.98 29.97 and so on. I have footage that was shot at 30P on a Canon 5D.
In a previous communication with you, you indicated I should transcode to ProRes from the 5D, for editing.
I’m a little confused.
Is there a special consideration I need to be aware of, or a special setting I need to make?
My file sizes from the captured media on the 5D are 4.7 times larger than the h-264 from the camera, does that sound right?
Also when transcoding would you still turn on re-compress frames? I believe the footage is already in I frame or does the H-264 change that?
Larry replies: Randy, if I said that ProRes only works with certain frame rates, I apologize, for that is not correct. It supports all known frame rates.
Converting your 5D to ProRes is straightforward, as I’ve done it myself. Be SURE to get the free EOS Movie Plug-in from Canon that allows you to use Log & Transfer for the process.
And, yes, ProRes is bigger, but provides much faster compression and higher image quality, especially for effects.
And, H.264 is definitely not I-frame based, which is why it is so tiny.
Keep in mind that if you use MPEG Streamclip to transcode your media, all your timecodes reset to hour 0. If you use the EOS Movie plug-in, your timecodes will match time of day when the recording was made.
UPDATE – Sept. 26, 2010
Ben Balser adds:
I deal with this a lot. “ProRes file sizes are huge!” Well, honestly, they’re not.
Let’s work with uncompressed HD, or DVCPRO-HD, any HD video format that is not Long-GOP, and that is “normal size” files for HD video. MPEG-2 and H.264 are actually TINY, TINY file sized, and very highly compressed, and have all the headaches, um, “issues” of Long-GOP video file workflow. So rather than think these highly compressed files are “normal”, let’s clear the air, they’re not normal HD video file sizes, they’re super tiny, very compressed.
Also, in reviewing the Canon EOS Movie plugin for FCP’s Log & Transfer process, it is quite a bit faster than using Compressor (Canon enhanced the algorithms to make it faster), and I’ve found, as fast, if not a tiny bit faster than MPEGStreamClip. Not to mention all of the other benefits you mentioned. And I’d like to ask you about one other issue on this subject. I know a few professional videographers out there using MpegStreamClip to convert the Canon DSLR H.264 files to XDCAM and other MPEG-2 file formats. What’s the purpose? I don’t get it. Why convert to another Long-GOP format, which will risk losing image fidelity/quality in the process? I’d love to hear a valid professional reason for this.
Larry replies: Thanks, Ben, for the update. I agree that using the Canon plug-in is the best way to work with DSLR footage.