It happens every week, sometime multiple times a week. I stare at my computer screen and think to myself, “What settings do I want to use?” I’m talking of course about the settings I will use for the videos I compress for online playback.
As you recall, yesterday I shared how back in the day, I used to export Windows Media Player (.wmv) videos. Then I upgraded to Flash (.flv). Now, with the onset of HTML5, I choose a format that yields the best combination of quality and compression. (I’ll get to the specifics in a minute).
Like yesterday, I feel a disclaimer is needed. Remember, I’m only a quasi-expert at this stuff. There are people like Jan Ozer who are a gajillion times more experienced than me (well, maybe not a gajillion. But at least 2-3 times. :) ) In fact, I wouldn’t be offended at all if you bounced from my site and just hopped on over and read all of his articles. I promise. You won’t hurt my feelings.
Okay, for those of you who stayed, let me say that I promise the information I give you will be relatively simple to understand, and it will be rooted in my real-world practices. What I’m sharing is how I do it. It’s not necessarily the right way. It’s just A way. Some of you I’m sure have better ways. If so, please share in the comments.
Okay. Here we go.
First, let’s cover a basic decision. What resolution to choose. Chances are, the majority of you are editing high definition (HD) videos. I’m talking 1920×1080 or 1280×720. This is what I’m working with. But it wasn’t always this way. If I may reminisce again, I remember when the videos I’d output were 320×240 (or 400×300 if I was being daring). This was back in the Standard Definition (SD) days. It’s just so funny to even think about that now. I look at some of my old video exports and think, “How in the world did people ever accept such teeny-tiny video).
Then, when I started shooting in a 16×9 aspect ratio, I stared exporting videos at 400×225 or 500×281. This was still an SD resolution.
Now my resolution of choice for videos I post online are 1280×720. In some rare instances I will export a video at full HD resolution of 1920×1080. But most video sharing sites default to a much lower resolution (960×540 or 640×360). As long as you upload a larger video, viewers will still have the option to choose a higher resolution if their monitors can handle it.
Of Bits and Bytes
Once you know what resolution you want, the next decision (and perhaps the most important) is what data rate to set. This is where it may get a tad more technical, but I’ll try to keep it simple.
There are bits and bytes. Approximately 8 bits make up one 1 byte. Most of the data rate figures you see will be in megabits per second (often written mbps). The capitalization is important. Because if you write MBps, this traditionally stands for mega-bytes per second, not –bits. But don’t be surprised if you ever come across an article using MBps, but meaning mbps. You’ll know by the size of the number. Here are some common numbers to give you perspective.
- The .MOV files in popular Canon DSLRs are compressed at approximately 45 mbps.
- The .MOV files in some of the most popular Nikon DSLRs range from about 14 mbps to 24 mbps (depending on the quality setting)
- The popular Apple codec ProRes 422 is about 145 Mbps; ProRes LT is about 100 mbps; ProRes Proxy is about 45 mbps
- SD DVDs range from 4 to 8 mbps
If you want to convert mbps to MBpbs, divide by 8. So those Canon DSLR files I mentioned above are just over 5 MBps.
So, what data rate should you choose. Vimeo suggests 2 – 5 Mbps for SD, 5-10 mbps for 720p HD and 10-20 mbps (fyi: kbps is kilobits per second. Approximately 1,000 kbps equals 1 mpbs. This is not to be confused with KB, kilobytes. And yes, there are about 8 kb for every 1 KB.)
Personally, I typically choose a compression rate of 4 to 7 mbps for my 720p videos. Partly this is because I think the quality you get is really good and I don’t want any playback issues for my viewers. But I also admit that part of it was because I use Compressor and choose the AppleTV format. This setting only had a range of 1500 to 5000 kbps (i.e. 1.5 to 5 mbps). If you have an amazing looking video with tons of detail or motion, you may want to opt for the higher rate. It pays to experiment.
Video compression is not the only compression to consider. There’s also audio. I typically keep the default 128 kbps setting. Vimeo suggests 320 kpbs. Wow! That seems high. But like I said. I’m only a quasi expert. But frankly, I’ve always used 128 kbps, and have yet to hear any issues.
Two more notes about compression. First, the video sharing sites you use will have their own video compression when converting your video to a web-based version. It’s worth looking into their information to find out what that is.
Second, most compression programs will give you the option to do constant bitrate (CBR) vs. variable bitrate (VBR) compression. CBR will compress the entire video at the same rate, say 4 mbps. If you’re not concerned about file size, this may be a good option as it’s faster and takes less processing power. VBR is a system whereby the computer will compress different parts of the video at different rates (you will enter some target or average rate). So high motion parts of the video will get a higher rate than say sections where there’s no motion at all. That way you can better optimize the video. Furthermore, there are two kinds of VBR: one-pass and two-pass. In one pass, the computer looks at the subsequent frames of the video and makes a prediction of the optimal rate. With 2-pass, the computer will look at the whole video once, then based on that first analysis, go through it again to make the best compression decisions. Two-pass VBR will yield the best combination of quality and file size.
Codecs and Formats
There are many different codecs to consider when exporting for the web. Codec is short for “compression-decompression.” It’s the algorithms used by the computer to compress large video files into something more manageable.
Video format are the wrappers used to hold those compressed videos.
As I mentioned yesterday, all major video sharing sites will accept all the popular codecs. So whether you’re a Mac or a Windows person, the format you export can yield a video people will be able to watch, regardless of operating system or browser. Here’s a run-down on some popular codecs:
- H.264: the popular codec used by most DSLRs and one of the top codecs used in compression for the web. It’s also the format used for Blu-ray disc compression. (Note: H.265 is on the horizon.)
- MPEG-4: another popular standard for the web. Most mpeg-4 videos have the suffix .mp4. But .m4v is also an mpeg-4 format (specifically it’s a video mpeg-4 format. .m4a is an audio mpeg-4 format).
- MPEG-2: format used for creating standard definition DVDs.
It should be noted that .MOV is not a codec. It’s the suffix for a QuickTime video, but that video could be any number of codecs. You can have an h.264 .mov file, a ProRes .mov file, an MPEG-2 .mov file, etc. Popular video formats on Windows systems include .AVI and WMV files.
As I also mentioned above, I export using Apple’s AppleTV preset (a .m4v, h.264 codec). I like it because it yields a high quality video with optimal settings for smooth playback. It’s also a format that is playable on popular mobile devices.
The Best Combination
- Who’s your audience?
- What are they most likely to be using to view your videos?
- What kind of video is it? (I would use a different set of settings for a guy talking on stage vs. a cinematic film shot in the Rockies.)
- How long is the video?
- Does the video sharing site I use have upload size limits?
- Are there bandwidth issues I have to consider (e.g. if you upload to a site that limits how much monthly bandwidth you get)
- Do you want people to have the option to download the original file?
- What formats does your video sharing site accept?
- Will your video sharing site automatically create multiple sizes and data rate for the video for playback on different internet connection speeds?
As you can see, there’s a lot that goes into picking the perfect recipe for your web-based video content. Here’s my usual recipe:
- AppleTV codec, h.264
- 4-7 mbps (depending on the video)
- Frame rate (source, which is usually 23.976, aka 24 fps)
- 128 kbps
What’s your favorite web compression combo?
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