Flash, FLV, and alpha channels: straight or premultiplied?

Todd Kopriva's After Effects region of interest features this guest post from Tim Kurkoski, an After Effects quality engineer, Flash, FLV, and alpha channels: straight or premultiplied?

The punchline is that Flash only supports alpha channels that are pre-multiplied with black.

RichFLV among Adobe AIR Apps to Check Out

Read/WriteWeb has a coupla articles on Adobe AIR, which was launched at the Adobe Engage 2008 event today in San Francisco: The Best Things About Adobe's AIR Platform and 6 Adobe AIR Apps to Check Out.

RichFLV (pictured above) seems cool; it let`s you edit .flv files and metadata.

There are more AIR apps at the Adobe AIR Marketplace, and John Dowdell and Ryan Stewart note other press coverage.

Update: Lee Brimelow has an article on Streaming Media on Building Video Apps With Adobe AIR.

Update 2: Adobe released a new version of the desktop color harmony browser kuler.

Adobe ships Flash Player with H.264 video

Emmy Huang and Tinic Uro , Justin Everett-Church, and the Flash Dev Center have the Flash Player 9 news with tons of further references.

And it's already being used by a big player; see NewTeeVee's Hulu Adds HD. Beet.TV noted details on the Hulu blog.

The release covers h.264/AAC audio on Windows, Mac, and Linux, and "improved performance through multi-core support for rendering, hardware scaling in full-screen, multi-threaded video decoding, a new algorithm for image scaling, and the Flash Player cache for local caching of common platform components to reduce SWF sizes and app loading times." Also, there's new stuff on Flash Media Server.

As noted here a few days ago, Tinic Uro previously mentioned a 'fast-start' trap on files compressed as h.264 in tools like AE and Premiere. For now "the moov atom (which is the index information in MPEG-4 files) is at the beginning of the file....you have to wait until the file is completely downloaded before it is played back. You can use tools like qt-faststart.c written by our own Mike Melanson to fix your files so that the index is at the beginning of the file." In Apple tools (or in CS3 with File>Export>QuickTime), you just check the "Fast Start" box.

FLV metadata & Adobe Encore

Some applications like Adobe Encore create Flash .flv video files, but don't tell you details about the settings beyond "High Quality." I'd like to see more control over FLV compression settings and metadata in CS4.

You can get a bit of info from FLV Player and VLC Media Player, although VLC has problems playing some files, including ones from Encore. Version 2 of FLV Player doesn't always show metadata, but it is prettier and plays at fullscreen with Apple-like play controls. In fact even if it plays only single files, it seems like a better player than Adobe's own AMP now in public beta.

Anyway, you can find some metadata easily in Windows XP with FLV MetaData Viewer, a property sheet extension DLL which adds 'FLV Details' tab to the file properties dialog of FLV files. This tool isn't quite free of a previous bug mentioned in earlier post File info for FLVs. If the property sheet works you won't get as much info as possible though, like the stuff shown in FLV MetaData Injector, also from the Manitu Group. With this tool you can generate an XML report showing the share of audio and video data rates.

I think that the audio portion of Encore's FLV is unnecessarily large, and I don't always want a 29.97 frame rate. There's more on these output settings in the technote Adobe Flash export in Encore CS3, but I'd like to see more control over FLV compression settings in Encore CS4.

AIR application 'Convert Final Cut Pro Markers to Flash Video Cue Points'

While not a problem for Premiere and AE users, Final Cut Pro markers don't work well as cue points in a Flash video file, while the UI for scrubbing and setting cues in Adobe's Flash CS3 Video Encoder is unwieldytiring of this, John Skidgel built an AIR utility to convert FCP XML to FLV XML, which you can import into Flash CS3 Video Encoder. You can pick up the app and check out the walk-through at Free AIR application: Convert Final Cut Pro Markers to Flash Video Cue Points.

John has also made available a few more tutorials from his Focal Press book Producing Flash CS3 Video: Techniques for Video Pros and Web Designers.

Flash Video Content Protection

Adobe has a new white paper with visual explanations of some of the risks for delivering video on the Internet and how to protect content from stream capturing by Real Player and other tools using the built-in features of Flash Media Server. John Dowdell has good background and extra linked resources on this white paper, Video Content Protection with Flash Media Server.

FLV settings for YouTube

Aharon Rabinowitz clarified how YouTube's updating of FLV settings changed from his article in the latest Cow magazine. YouTube stopped accepting FLV, so you're stuck with their compression and mono audio. I previously had good luck with QT Photo-JPEG at 320x240 and 15fps, but he had AV sync problems and recommends WMV submissions for best quality getting under the 100MB limit.

File info for FLVs

I've tried various utilities and players (VLC, Riva, FLV Knife, etc) to show file info for FLVs (Flash Video), but without much luck on many files. One hope was FLV MetaData Viewer (FLVMDV), a property sheet extension DLL for Windows XP that adds an 'FLV Details' tab to the file properties dialog of FLV files. But I couldn't get it to work at first.

Happily, I noticed that FLV Player (Windows) does show video data rate and dimensions. And when I installed the handy SUPER, another Windows compression utility that uses ffmeg (command line on PC) for some tasks, the "FLV Details" property tab finally showed up in newly created -- or copied files (CTL-drag) -- files but only in SUPER's output folder!

Now I get info on sample rates and AV codecs used (On2 VP6 or Sorenson H.263), but I still need FLV Player for video data rate, if that metadata is added by the authoring tool. It sure seems like Adobe should be making this stuff easier -- if they see a future in digital video.

Update 03.12.07: VLC does give basic info, except average data rate, on almost all files (FLV1 is the Spark codec). VLC just has trouble playing and scrubbing some FLV's.

Once reason for concern with Flash metadata is that there's been bugs in most FLV compression software possibly since so many, like YouTube apparently, rely on FFMPEG. Duration and dimension metadata of a file is not always correctly saved, according to Jeroen Wijering, hence the concerns with FLV Knife and FLV Metadata Injector. He also notes: '...on movie scrubbing; Flash seems to only scrub to keyframes. So if you compress a movie with very few keyframes, the scrubbing won't run very smooth. Compress with more keyframes (can be set in nearly every compression tool) to get rid of this problem." My lack of understanding all the problems wth Flash encoding, players, cue points, seeking, and preloading prevents me from preferring Flash over QuickTime or even Windows Media.

BTW, WinFF is another freebie GUI for FFMEG. Mac users have it easier (fewer but better freeware) with ffmpegX and Visual Hub.

Free FLV web services

Services like KeepVid let you to save an FLV from it's website.

VIXY goes a step ahead and lets you submit an url then they convert the video and download the converted file automatically to your hard drive. VIXY allows you to convert a Flash Video FLV file (Youtube movies,etc) to MPEG4 (AVI/MOV/MP4/MP3/3GP) file online. VIXY is using a compressed domain transcoder technology and converts FLV to MPEG4 faster with better quality than a typical transcoder.

Details on saving FLVs and converting them

Here's a detailed tutorial for different browsers and OSes:
How to Copy Files Off YouTube and Convert them for your Video iPod, which mentions MoviePod (Mac/Win), another app that converts movies, with a single Drag & Drop.

And via DVGuru, a quite comprehensive Amazing YouTube Tools Collection from Quick Online Tips.

Update 10-26-06:
There's even a YouTube movie that explains how to get things off YouTube.
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FLVTool2: Flash video and meta data manipulation

Some compression apps don't support Flash Cue Points, so this might help:
FLVTool2 "can calculate a lot of meta data and insert a onMetaData tag. It can cut FLV files and add cue Points (onCuePoint). A debug command lets you see inside our FLV and the print command gives you meta data information in XML or YAML format."

And here's where I'm storing my link to Perian (requires OS 10.4) a plug-in for Quicktime that allows play of files encoded with a non-standard codecs like FLV, XviD, or 3ivX. And if I forget Flash Developer Center.

Encoding Flash Video

Flash 8 Video Encoder's settings are explained in FLV Data Rate and Bandwidth... Demysitifed" at Community MX -- and republished as Encoding Flash Video by Adobe Design Center.

Word on the Adobe street is that FlixPro handily beats Squeeze with about a 4x compression time and good quality in default 2-pass VBR settings. We can do 1-pass just fine with the Adobe Exporter!
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Convert FLV Flash files to movies

If a friend needs to convert Flash videos files (.flv) to QuickTime, iSquint (Mac OSX) is very easy and has some advanced controls. A companion product VisualHub expands options further, but iSquint did a great job getting 'Gangsters' by The Specials to iPod format.

On Windows, there's the freeware apps Videora Converter. swf2avi and Riva FLV Encoder. I didn't try them, but there's a ton of pay products for Windows like ones by Wildform and On2.

At some point I wanted to find out what the fps rate of an FLV and can across FLV Knife, a handy Windows tool to view or cut flvs, and inject metadata. BTW, the Video LAN player VLC (Mac/Win) seems to play anything especially the Windows version.