So we’ve always planned to make the source code available for Buttercup. Now it’s time to think a bit more about how exactly we go about that. Given the nature of the project there are a few things to think about.

We’ve really got two key goals that we’re looking to achieve by shipping the source.

1. We want people to learn from our code and be able to make their own Silverlight apps accessible. This probably won’t involve reuse of a lot of our code, but, it will probably see you pouring through the app getting ideas.
2. We want Buttercup to live on, grow and continue to be developed. To get this to happen we really need to build up a bit of a community of enthusiasts to work on it. That’ll involve some of the original team but it’s going to need a bunch of ‘new blood’ to help drive things along too.

So my current thinking is to release the source code via a CodePlex project. We (the Intergen team) will probably take the role of project administrators for the first wee while and will probably look to vet initial patches into the source tree. We’ll then look to bring on other developers and project leaders nice and quickly.

So I’ve got a few questions for our interested community.

1. Shall we make the code available now? Or should we wait until we’ve ported it to Silverlight 3.0?
2. What licences do you prefer? I’d like to use one of the OSI approved licenses and ideally something that is notCopyleft. Current leanings are BSD, Modified MIT and MS-PL. But I’d love to hear from the community interested in Buttercup what your thoughts are.
3. Are you interested in being involved in the on-going development of Buttercup? It’s a Silverlight 2.0 application written in C#.

Please use the comments to provide some feedback. We look forward to hearing from you.

So, one of the cool things we aimed for with Buttercup was ensuring that we not only worked well with screen readers, but, that we worked well without screen readers too. If you think about scenarios like the public library, chances are they will not have a screen reader installed but Silverlight is a much better probability.

To achieve this we wanted to support the idea of a self voicing UI. We did this, but, it comes with quite a few caveats. This includes the fact that it only works in Internet Explorer and even then you’ve got to do some security acrobatics to enable the Active X calls that we make.

I’ve been kicking around a few ideas of how we might improve the self voicing experience. I’m big on doing this because it’s inherently re-usable functionality. if we can get cross browser self voicing working it’ll allow us to ‘Self Voice’ not only Silverlight applications but also plain old HTML apps as well.

So, some of the thoughts I’ve had:

• Pre recorded MP3s for UI elements. Basically we’ll create an MP3 to be played by the UI when you button hover or field focus.
  This is pretty easy to achieve, but, it has a few draw backs too. We will only be able to support static speech- if you run a search in Buttercup today we’ll actually speak the result count back to you. Using pre-recorded MP3s is also a fairly time consuming process- we’ll either need to use voice talent, or generate each MP3 using a synthesizer and package it up. Sure we could probably build a tool that used reflection to interrogate the UI Automation tags and then created the speech files. But, overall this still feels a bit fugly to me.
• Calling up to the server. We could make a web service call to the server passing up the speech we’d like generated. We could then use one of the variety of Text to Speech generators server side to create a speech MP3 to be returned to the client. We’d obviously do some caching on the client and probably push this cached data into isolated storage to persist across runs. This gets us around the dynamic generation limitations from above, but, gives us a server side dependency which is something we’ve thus far managed to avoid in Buttercup- we really want people to just be able to grab the Buttercup *.xap file and stick it on their site. Making server calls doesn’t really suit this model. I’m also not 100% on whether the latency will be tolerable- realistically we’re probably talking 3000ms at a minimum. I think if we did go this way it’s probably only be a stop gap and we might just run the speech gen service in say Windows Azure.
• Generating the Speech in Silverlight. This is kind of the nirvana. In Silverlight 2.0 (which is what Buttercup is currently built in) we just can’t do it. But, Silverlight 3 we have the ability to use the new MediaStreamSource and this might just let us do some sort of Audio generation. I think that we’d probably need to look at porting an existing open source TTS engine to C# managed code and then surfacing this into Silverlight. I’d love to get feedback from anyone who has had good or bad experiences with any of the open source TTS engines.

Now that 3rd point got me thinking about another commonly requested feature- variable speed playback. The Silverlight 3 Beta doesn’t support variable speed MP3 playback and it doesn’t look like it’s a feature that we’ll get in this release. It might be possible, though, to build a custom MP3 decoder to support this feature- maybe a port of MP3Sharp.

Anyway, that’s my braindump for today. I know that Andrew Tokeley will have some interesting samples to post after his Twilight Session tomorrow. I’d love to hear in the comments if people have other ideas for the above problems.

One of the cool features of ButtercupReader is the ability to open DAISY books that you have published on your own web site. Once you’ve followed the few simple steps below people will be able to link to your books using a link that looks something like,

All you are doing is setting the ref query string parameter to the URL of the package file (*.opf) that describes your book. Easy.

Now, in order for this to work there are a couple of things that you need to do on the web server that is going to be hosting the DAISY book files.

Add MIME Types for DAISY File Extensions

In order for your web server to be able to serve up requests for DAISY files you will need to add some additional MIME types. Currently the only file extensions that ButtercupReader relies on are,

Allow ButtercupReader Access to Your Domain

By default Silverlight is not permitted to access resources (like your DAISY files) on another domain (like your web site). But this is easy to fix. All you need to do is to add a file, naming it clientaccesspolicy.xml, to the root of your web site. This file should look like,

For more information check out the official documentation.

So, give it a try and let me know how you get on.