Understanding compression settings...

[Gregory Stevens]

Hey all, I figured this section of the forums was perfect for my question...

I have never been able to fully understand compression settings, between the fact that there are just so many options and that you almost always find someone telling you "these settings are the best!" I want to better understand what every setting means. I understand this will probably entail a lengthy response but if you have the time or have a website that goes into full detail - I'd really appreciate it.


Also, I use a Canon XH-A1 for my shootings, when I want to upload to a site such as YouTube or Vimeo using the "Windows Media Video V11" codec - What are the best settings to optimize quality and reasonable file size? I've also read "HDV 1080-60i (1440x1080, 29.970 fps)" format does not have a "true" HD pixel ratio which I do not understand - maybe my project settings for my XHA1 should be "HD 1080-60i (1920x1080, 29.970fps) ??

I use Vegas Video as well.

Please help someone super confused.

[Sareesh Sudhakaran]

the only way to learn is by doing it, and the only person who knows what is acceptable is you.

Youtube has delivery standards, and you need to encode your video to their standards. Vimeo accepts a few different file types, etc.

Then watch your video on Youtube, etc and see if it best represents your vision. If it doesn't, you need to go higher on your settings. If it does, then go 'lower' on your settings until you find a perfect size-to-quality balance. It's different for every project, every camera, every region, etc. There is no magic formula.

[James Palanza]

I could also use a bit of a catch up on some of these settings. I mostly use premier and there is just an outrageous amount of compression options. Any suggestions? As far as I know, its important to keep your captured frame rate the same in your project and sequences/renders/compression.

Aside from that I start to get a bit befuddled with the ton of codecs available. I've been using my black magic uncompressed 8bit HD YUV setting for exports once I have the project done (to move to after effects for further editing, etc)

Any other info out there? Better way?

[Jordan Hooper]

Optimizing your video uploads : Learn More - YouTube Help

[Gerd Kogler]

Gregory, look at the 'HDV Progressive Primer' from Sony online, its about 25 pages and it gives you an easily understandable insight into HDV technicalities including compression (about 25 pages).
Hope that helps!
Gerd

[David Beisner]

Originally Posted by Gregory Stevens

Also, I use a Canon XH-A1 for my shootings, when I want to upload to a site such as YouTube or Vimeo using the "Windows Media Video V11" codec - What are the best settings to optimize quality and reasonable file size? I've also read "HDV 1080-60i (1440x1080, 29.970 fps)" format does not have a "true" HD pixel ratio which I do not understand - maybe my project settings for my XHA1 should be "HD 1080-60i (1920x1080, 29.970fps) ??.

Hey Gregory,

I also use the XH-A1 and can give you a few tips. First, in response to your question about it being "true" HD pixel ratio--1080 and 720 HD has a square (1.0) pixel ratio while HDV has a 1.333 pixel ratio in order to maintain the same 16:9 framing with the available pixels. Perhaps thinking in terms of blocks might help you understand that if that's not clear in your mind. Imagine you were creating your image with building blocks. In order to get a final image that is 16:9 (sixteen units wide by nine units high), you will have square blocks, with 1920 blocks width-wise and 1080 blocks height-wise. However, if you wanted to get the same 16:9 ratio with HDV, which only allows you 1440 blocks wide instead of 1920, you need to stretch the width of your blocks by 1/3, giving you blocks that are 1.333 "inches" wide by 1 "inch" high, instead of the truly square blocks you would have with 1920x1080 or 1280x720. If you were to change your project (or export settings) to 1920x1080 and feed 1440x1080 video into it, you will EITHER have black bars on the sides of your video frame OR you will have video that is stretched width-wise. So not a good choice. Always stick with the original aspect ratio of your shooting.

Ok, hopefully that's cleared up the pixel aspect ratio for you. I don't know what your NLE is or what you use for rendering, but I'll give you the settings I use with the Adobe Media Encoder CS4 that is bundled with Premiere. I create promotional and news video for a college and we have two places online where we put our video: our collegiate website, and YouTube and Facebook. For our website we use the Adobe Flash Streaming Media Server which allows us to upload multiple qualities and the server will automatically switch between qualities depending the user's internet connection and computer speed. These settings pretty faithfully represent my HD video source (with a much smaller size, as you'll see when I get into them). Our lowest codec is designed to run on an internet connection at 250k, our medium at 500k, and our highest at 1000k. Anyone with a DSL connection will get the 500 or higher, and the 250 actually runs half-way decently on dialup if you let it buffer. Finally, for our Facebook/YouTube videos (and we also use these same settings for running videos on HD digital signage we have around our campus) I use higher quality settings at the equivalent of 720 HD screen size. FYI, our HD settings were taken directly from the recommendations given by Vimeo for 720 HD video hosted on their servers). Also, just as an FYI, most of my video is shot at 60fps and encoded at 29.97. Some things are shot at 24 which is encoded at 23.97, but only when I'm working on a project that I want to have a film-like feel. So, here are my settings. Note that all four settings are encoded using the MainConcept H.264 Video encoder.

Lowest bitrate:

512x288 pixels (width x height)
29.97 fps
Aspect: Square pixels
Field Order: None (Progressive)
Profile: Baseline
Level: 3.1
Bitrate Encoding: VBR, 1 Pass
Target Bitrate (Mbps): 0.2
Maximum Bitrate (Mbps): 0.25
Set Key Frame: 15 frames


Medium Bitrate:

512x288 pixels (width x height)
29.97 fps
Aspect: Square pixels
Field Order: None (Progressive)
Profile: Baseline
Level: 3.1
Bitrate Encoding: VBR, 1 Pass
Target Bitrate (Mbps): 0.4
Maximum Bitrate (Mbps): 0.5
Set Key Frame: 15 frames


High Bitrate:

512x288 pixels (width x height)
29.97 fps
Aspect: Square pixels
Field Order: None (Progressive)
Profile: Baseline
Level: 3.1
Bitrate Encoding: VBR, 1 Pass
Target Bitrate (Mbps): 0.8
Maximum Bitrate (Mbps): 1.0
Set Key Frame: 15 frames


HD quality for Facebook/YouTube:

1280x720 pixels (width x height)
29.97 fps
Aspect: Square pixels
Field Order: None (Progressive)
Profile: Baseline
Level: 3.1
Bitrate Encoding: VBR, 2 Pass
Target Bitrate (Mbps): 1.5
Maximum Bitrate (Mbps): 2
Set Key Frame: 15 frames


Both Facebook and YouTube read that last one as actual HD video and mark it as such, and it gives me an EXTREMELY good representation of my original HD source. For all encoding bitrates (Low-HD) my audio settings are AAC, 128kbps, 48kHz, Stereo. Also note that with AME your Aspect can be set to Square pixels or 16:9 Widescreen and it'll give you the same result.

When I first got into the industry I had about 3 months before purchasing was able to get me equipment to work with so I spent those first three months reading and researching online in forums such as these and learned quite a lot about encoding and bitrates and such. I found Wikipedia's articles on all of these subjects to be particularly helpful to me.

Good luck!