MPEG2 outputs using max bitrate instead of target
Red Planet Pictures Nov 14, 2012 2:51 PMBack in CS5, I created a preset specific to a TV station client's specific broadcast needs for HD content. In a nutshell, I used the MPEG2 HDTV 1080i 29.97 High Quality preset, changed quality to 5, and minimum, target, maximum bitrates to 15, 30, and 50, respectively (in mbit/s). Nothing else was changed whatsoever, and the estimated file sizes were usually around 5GB. It worked like a charm, and the files always came a couple hundred megs within the estimated size.
So fast forward to last week, now on CS6. I reload CS5, export the preset, import to CS6. So far so good, triple-check that every setting is exactly the same, estimated file sizes are still around 5GB. I output the movies and they come back nearly twice the size, all pushing 9.5GB. Opening the videos in both Quicktime 7 and VLC and viewing movie properties reveals that their bit rates are 50 mbit/s, while doing the same for the old, smaller sized episodes are at the proper 30 mbit/s.
Again, I triple checked to be sure the presets were the same. I am absolutely certain there are no differences in the settings, but for whatever reason, CS6 is ignoring the target bitrate and instead making the videos the maximum. Similarly, the same thing happened with an SD 720x480 output. Took the old preset from CS5 which worked fine, imported it into CS6, and in this case the file size nearly tripled. The files are still usable by the client fortunately, but it creates a hastle for us as transfer times and capacity are doubled. A workaround could be changing maximum to match the target rate, but obviously there's a quality sacrifice there, and that's not really a solution anyway. The whole point of min/target/max settings are for variable bit rates to achieve maximum quality with minimum size.
I will say one thing that just occured to me is I haven't tried 2 pass encoding. Given how long these episodes tend to take and the time crunch of our environment, I can only ever remember 2 passing an encode once, definitely not for these clients. I do remember though that the 2nd pass made a huge impact in a smaller file size. I'll leave one encoding overnight and see how it comes out in the morning. It's possible I just don't remember doing it on the older episodes.
All that said, has anyone else encountered this? Is there a fix? Did I just hit the nail on the head? Cheers,
[UPDATE]
2 pass encoding didn't make a difference.
Jeremy
System specs:
OSX 10.6.8
Creative Cloud CS6, all up to date
16GB RAM
Geforce 8800GT


