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Best Quality Compression Settings Blu Ray h264 (yes, I know…)
Ok, let me preface this question with the following. I do know that selecting the settings for best quality depend on a range of issues, and that one should do tests and compare. I also know that one should render out an uncompressed file from AE and then use AME for encoding. I have a basic understanding of the differences between CBR, 1 pass and 2 pass; and I have a less than basic understanding of target rate (Mbps) issues. But I have a very specific case here, that maybe someone can either answer or point me to the right place.
I am producing abstract color art using AE. Resolution 1920×1080, progressive. The final product will be a blu ray disc to play on a blu ray video deck. And the video is only 20 minutes long. Color and image quality are the most important things (obviously this would be the case for most people). I don’t really need to worry so much about compression for file size, since even barely compressed it would still fit on a blu ray disc. But I do need to worry about the target and maximum bitrates (which as mentioned I don’t really understand). From what I’ve read I believe that I should be using H.264 Blu ray compression.
Other than that, can someone tell me how to get the best quality?
–ds
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4 Replies
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Hi Dennis,
Variable Bit Rate (VBR) encoding is helpful for long videos, but I see no benefit for short clips. Just use CBR and crank up the rate, perhaps 30 or 35 and that should look great for you. As you said, “H.264 Blu-ray” encoding should be used. Don’t mess with any other settings besides CBR/VBR and bitrate.
You said the material is progressive, but didn’t note the frame rate. Blu-ray does not support 1080p30 – AME only has presets for 1080p23.976 or 1080i, so if your video is 1080p30 then try the 1080i Blu-ray encoding preset.
Doesn’t apply for CBR, but regarding the VBR question – the Target bitrate will be the “average” bitrate, with the Max of course being the highest rate that would be used on more complex scenes. Think of VBR as “Bit Budgeting”. With long videos (couple of hours), you want to best allocate your resources, meaning available space on the disc.
No sense in encoding still images, title pages, low-action scenes at the maximum bitrate when they will look just as good encoded at a low bitrate. Using the lower bitrate for those scenes “frees up” additional bandwidth so that you can encode complex scenes at a data rate higher than average. You’re just making the best use of the available space on the disc, applying the appropriate amount of compression to each scene to maximize quality. With two-pass encoding, the first pass analyzes the footage to determine the complexity of each scene, which therefore allows the second pass to encode each scene at the optimal rate. For short videos, just use the high bitrate with CBR, as you have room to spare!
Thanks
Thanks
Jeff Pulera
Safe Harbor Computers -
Thank-you for that thorough reply. Just one last question about bitrate, that has been bugging me for some time. I understand the budgeting concept as far as space is concerned. But does bitrate have anything to do with playback devices. That is, is there a point at which the bitrate could be too high for the playback device?
You raise an interesting point about the 30fps progressive not being an option, which I didn’t know until now. I totally understand interlaced vs progressive, and I’m thinking that for slow moving patterns (especially with thin horizontal lines) that 1080p23.976 would be best. Do you concur?
thanx again. –ds
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Hi Dennis,
My understanding of encoding 1080p material as 1080i is that you don’t get the interlacing issues you’d have if the source material was interlaced – you should not have an issue going this route.
If you encode 1080p30 down to 1080p24, keep in mind that you have less frames per second, which is going to produce more jerky/stuttery motion, probably not what you desire.
As with DVD, Blu-ray has a “maximum data rate” prescribed by the official Blu-ray spec. However, with DVDs or Blu-ray discs, the discs we burn at home are different than a commercially-made disc that is stamped out (replicated, versus duplicated at home). Burned discs, due to the media composition, could potentially have playback issues with some players when pushing a higher data rate.
While the DVD spec allows for about 9.4 total (video and audio), most users will limit the video data rate to 7 or 8 max for safety. I believe Blu-ray allows for about 40, but there is a point of diminishing returns. Does 30 look obviously better than 25, or 35 much better than 30? Most of my Blu-rays are 2 hours or more and look great to me at say 20, so how much “better” can 35 look if 20 already looked just fine?
So what I’m saying is, don’t think you need to approach the upper limit of the spec to have a great picture. I’d prefer wider playback compatibility over squeezing out that last 1% increase in image perfection.
Do a test – encode a short clip at few different data rates and just play them back on the computer and compare quality between then, and you may not perceive any difference. I think you’ll find 30 or 35 to offer outstanding quality, but be your own judge.
Thanks
Jeff Pulera
Safe Harbor Computers -
Thanx for the fast reply. One last simple question. Is there any software (Adobe or otherwise) that can actually display bitrates of a video as it is playing in order to see just what is happening with an encoded video? I would think that this would be a helpful tool for judging the issues you raise above.
–ds
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