Guys, don't be giving your money away that easily. I've done my own tests and found out that x264 PRO for Premiere is a perfect example of overhyped product. I was really excited to find out someone turned x264 into a Premiere plugin, so I decided to give it a try. Sadly, after a few tests I realized this plugin is a total waste of time. First of all, it's much slower than MainConcept H.264 codec, found in Adobe CC package, and I honestly don't see, how it's better quality-wise. Secondly, it creates more artifacts than original x264 freeware codec. And thirdly, it shifts colors of the material you are encoding. I don't see why anyone would spend 299$ for this thing.
But, I won't waste your time babbling unsubstantiated statements. Alllow me to present you some actual figures. I've converted my recent 12 minutes 12 seconds long 1080p project (STARS Academy at the 18th WCOPA Event on Vimeo) using Adobe Media Encoder CC 2014 v8.0.1.48 (MainConcept and x264 PRO codecs) and MediaCoder v0.8.32.5660 (x264 original codec). The Vimeo version is reduced in quality and size, of course. My conversions were made from nearly lossless Full HD material. All codecs were set to 12 Mbps target bitrate, 24 Mbps maximum bitrate (except original x264, which didn't offer max bitrate setting), High profile, VBR 2-pass encoding, AAC 256 kbps audio. Both x264 codecs were set to Film picture tuning and Very Slow encoding quality, because I wanted to see the best possible result that I can squeeze out of each codec at a given bitrate. Timewise, the results are:
1) MainConcept = 0 hours, 32 minutes
2) x264 original = 1 hour, 34 minutes
3) x264 PRO = 2 hours, 5 minutes
Original x264 completed conversion 25% faster, then x264 PRO, while Adobe's MainConcept implementation did it almost 75% faster! Of course, if I would have set x264 encoding quality to Medium, the difference wouldn't be so substantial. But wait till you see, how these encodes differ quality-wise. Seriously, after comparing the 3 results side by side I became a fan of Adobe's native H.264 encoder. It's super-fast, and it does a great job of preserving fine lines and keeping artifacts to minimum. It does so at a cost of some details becoming washed off. If we are to compare original x264 vs MainConcept, there is room for discussion, which coded and under what circumstances is better. But if we are comparing any of these two against x264 PRO by 3am Digital Studios, the answer is obvious to me. There is nothing about x264 PRO that makes it a winner. It's slow, it shifts colors pretty bad, and it's an excellent artifacts generator.
Let me show you. The following are 100% magnified 720p crops from the 1080p material. In each comparisson I got 10 screenshots that I picked randomly. They're all compressed to nearly lossless JPEG (you wouldn't be able to tell the difference between the original and Photoshop's Save for Web Quality 80). So, just move your mouse cursor over each screenshot to see, how codecs performed against each other.
MainConcept (32 min) vs x264 PRO (125 min)
http://screenshotcomparison.com/comparison/94302
x264 original (94 min) vs x264 PRO (125 min)
http://screenshotcomparison.com/comparison/94303
MainConcept (32 min) vs x264 original (94 min)
http://screenshotcomparison.com/comparison/94304
Obviously, Adobe's MainConcept H264 codec is great. However, I do agree to the common opinion that x264 is a better choice. Even, when I switch it to Medium quality, it takes 34 minutes to encode, while the resulting picture still has more details then MainConcept's result. At the same time there are no ugly encoding artifacts, such as those from 3am Digital Studios implementation. 3am developer(s) should do a better job implementing x264. At the moment it's a waste of time and money.