The movies are generally 30-60 minutes long and eventually get uploaded to Vimeo
They are edited in Final Cut and begin as ProRes 422 files captured with a BlackMagic thunderbolt box
My Compressor Settings are as follows:
frame rate set to current
key frame to automatic
Compressor Quality - high w/ Best Quality (Multi-pass)
Data Rate - restrict to 4000 kbits/sec
Optimzied for - streaming
acc, sterio 44.100
best quality & 128kbps target bit rate
dimensions set to 1280 x 720
I'm not seeing a setting that allows me to chose Constant or Variable. Is there any h.264 that will allow Constant? I'm just concerned that I'm getting the quality I'm looking for when I set it to 4Mb per sec but get just over 2Mb/sec in the outputed file. It seems so extreme that I was wondering if I bumping into some sort of bug in Compressor. I also output to the 1080P for Apple Devices 10Mb and it is always close to 10Mb/sec - never 50% less or even 2Mb/sec off.
Let me come at this from a different direction. If you go to Vimeo and review their compression guidelines, they specifically recommend that, if possible, encodes for uploading be VBR. There is also a link to a Compressor 4 tutorial on that page, and while I don't do everything their way, I do think it's a good tut.
Some compression apps give the user more flexibility than Compressor historically has…Adobe's Media Encoder for one. I've used the past three versions of Compressor and to the best of my knowledge, none of those provided a way to cobble together an h.264 CBR option. Other codecs, yes…you can do CBR. That's why I said that if you absolutely needed CBR (which I don't think you do), use one of the MPEG4 presets with MPEG4 compression. ∫ut it won't be as good as quality as an h.264. On the occasions I've needed an h.264 CBR I've gone to another app…again, like AME.
After reading your post, I took a three minute MP4 video, encoded h.264 VBR, with a target rate of 4 Mbps. It was a segment of two talking heads. When I played it, the reported bit rate was typically in a range of 3.2 to 4.5 Mbps…except when the interview was done and the talent stood up, the rate briefly spiked to nearly 7 Mbps.
My suggestion is that you experiment with some short sections of your work…using a range of bit rates with VBR encoding – bearing in mind Vimeo's recommendations. Upload these short tests. Then see what you think. Remember, Vimeo is just going to re-encode anything you give them for progressive download. The more video information you can give them in your upload file, the better.
Let us know how it works out.
I've got it now. The key was understanding what opitmized for "streaming" and "download" are. When "streaming" is selected it creates video with a variable bit rate. When "download" is selected it creates video with a constant bit rate.
Since Vimeo already goes through the process of coverting the video to a variable bit rate, I figure it's best to send them the full data, constant bit rate, video.
Thanks very much for helping me figure out what was happening.