best format, bitrate for video file distribution

[Terence Murphy]

We're looking at changing our main distribution format from DVD to encoding short sport clips (about a minute apiece) into a format of choice, and copying onto flash drives for our customers on site (typically 4-40 clips per person, and they'll be able to add files at later dates space permitting).

We're filming in AVCHD, 1080p60 28 MBps (Sony CX700v), and need to downsample into a format that is reasonable for most computers to handle (I expect most customers to have bottom-end Windows PCs). What is a good minimum common denominator resolution, codec, and bitrate to use that most people will be able to play? I've been fiddling with both h.264 and mpeg-4, either 1920x1080 or 1280x720, and 6-8 MBps, and everything plays just great on my quad-core MacBook Pro (including the original 60p footage), but it all has problems on my 3.5 year-old MacBook Pro (Core 2 Duo, hardly a slouch speed-wise). It also all fails to play well off a flash drive in my LG BD-390 Blue Ray player. I found someone else on the web distributing similar videos at 1280x720 5 MBps h.264 in a MP4 wrapper, and I have similar problems with them on the old MacBook Pro and the LG player.

But the old MacBook Pro can play HD footage from an iPhone (1280x720, ~10 MBps), so I'm not sure why it's having problems with my downsampled files.

I've tried encoding with both AunSoft's MTS Converter, and with QuickTime 7. Any recommendations on the best way to encode, and what format/res/bitrate that our customers will be able to play without problems?

-Terence

[Seth Bloombaum]

As you know, there's no one right answer, and several places to do some optimization!

First, yes, I'd encourage you to go 720p. It's really the best size for the most people, looking great full-screen on almost all laptop and desktop displays.

Second, the actual compression - QT isn't the best, which means that FCP and Compressor aren't the best, since they're built on QT. In this case "best" means best picture quality for a given bitrate.

You're going to want to select some high-motion footage that's representative, and do some test encodes in which you progressively starve the bitrate. As you get down to the lower bitrates, say, below 2Kbps, you should start to see better performance from your older macbook.

As to what encoder to use, I've been having good success with Handbrake (open source). I think it's available for mac as well as PC. I've not specifically tried to create an MP4 for QT Player on the Mac, this might require some experimentation. One of the things that HB does particularly well is deinterlace and resize - that's where it all starts... with progressive footage (is it true prog?), you're one step ahead, but the resize quality is very important, too.

Bearing in mind that if you're covering sports, you have challenging footage to begin with, it's important to recognize that any source in which every pixel changes on every frame is more likely to show compression artifacts, and require more bitrate to get rid of those artifacts.

"Every pixel every frame" usually means noisy footage, due to gain or camera issues, or handheld, esp. jerky handheld...

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I just reread your post. For low-end, especially older windows PCs, h.264/mp4 is a codec that can require a lot of processor power for decoding. WMV is great for PC, but not for mac...

Most modern methods for cross-platform performance depend on internet distribution, where you can control what player is in use. There, Flash VP8 is most compatible to older computers. For flash-drive distribution, that doesn't work as well since there isn't a conventional desktop "player" for flash video. It would call for more programming skills...

[Terence Murphy]

Thanks, Seth. I tried Handbrake -- I can't tell much difference in quality but it is faster than QT7. Is there any variation that allows trimming of input clips?

And I figured out my problem with playback wasn't related to the computer or LG player, but a bad Flash drive that I was using to transfer files and/or playback from. It seems it was corrupting my files, sending me on a wild goose chase!

It turns out the old MacBook Pro can playback 1920x1080, 30 fps, 6 Mbps h.264 and 1280x720, 30 fps, 10 MBps just fine. A 1920x1080, 60 fps, 8 Mbps file plays quite well, but only at ~30 fps, so that seems to be its limit.

The LG player also did fine with the 1280x720 file, and I haven't tested the 1920x1080 files yet. Seems like they should play -- they're still a much lower data rate than Blue Ray.

So now it's just a matter of making a bunch of test files, and finding a minimum spec computer to test on. But perhaps not my old 1.2 GHz iBook G4 -- hopefully we don't need to support playback on something that old....

-Terence