Yet Another Fricking Blog

So I hacked in the menu items, and they worked fine… sort of. I clicked ‘Play’ (or pick the menu item… or hit ‘P’, heh heh) while Input 5 (compy) was selected, and the i.Link mode ‘took over’ the display. Sweet. Then I hit ‘Stop’ (Actually, I had to press ‘S’, etc.) and it stopped. Sweet.

Except when it stopped, it didn’t return to the last Input. It just went to the digital TV tuner. Which I guess makes sense, because i.Link MPEG Transport Stream decoding is almost the same thing as showing live digital TV, there’s just a slightly different source for the stream.

This made me realize that the last thing I wanted to add was the integration of serial port control, strictly optional of course… since I’d already had success with that. But I opted to make it a little more generic, in case anyone else wants to use this for some other purpose.

I added a few NSStrings to hold paths to a user’s ~/bin directory, plus ‘vdvhs_on_stop’ or ‘vdvhs_on_play’, and matching bools to note whether there was an executable at that location. The applicationDidFinishLaunching method is where those checks are performed.

Then I created methods to execute the shell scripts, if they existed, by using the system() call. I initially had problems with these because I didn’t realize I had to retain the strings after I set them. So I was having an autorelease problem. Trying to access my NSStrings’ contents, and conver them to cStrings, was causing the program to crash with signal 11, SIGSEGV. When I went in with the debugger, I was able to see that the contents of my NSString was ‘Invalid’, and that was a big clue.

Once that was fixed, it worked pretty well! I’m on the fence about whether to use the ‘play’ script in my personal setup; if you switch to i.Link mode using the remote, or serial controls, it puts up the on-screen transport control (play, pause, etc.) and that’s kind of annoying. I did program the universal remote with the i.Link button (so as to get it off the screen) but I don’t know if I’ll use it that way or just disable the ‘play’ command shell script. Either way, I was pretty geeked when stopping the program also switched the TV’s Input back to the Mac. So, mission accomplished!

This is fun, but also kind of scary. I actually found myself looking over this page, which is Seth Mattinen’s recounting of his own experiences hacking on vdVHS, and wondering, “Hmm, how would *I* implement those features… wonder if he’d give me some advice…” Heh.

I believe that I finally have hacked together a version of Virtual DVHS that does what I need it to do… including keyboard control with hotkey equivalents (no modifiers).

I finally managed to flag down someone else from #macdev who was able to help me with my code. Turns out I needed NSWindow in place of NSResponder, and didn’t need one of the methods I had in there. In Interface Builder, I had to pick the ‘Window’ and choose my Custom Subclass from a list. I was… sorta close?

Anyway, I got it working with spacebar (play pause) and escape (stop), but the problem was, only if I didn’t actually click on anything in the window. As soon as I did that, my methods (attached to a custom subclass of the NSWindow) lost focus and stopped working.

My next thing to try was to use a menu, with hotkeys instead. I eventually figured out that the terminology is ‘Submenu’ to add a new menu, and ‘Item’ to put something in it. I created a Control menu, and Play, Pause, and Stop items. Made each of them corresponding IBOutlets in the .h file of the controller class.

The last thing to do was, connect these items to the same IBActions that clicking the buttons did… and also setting the ‘enabled’ state of each menu item in the same places where the button’s states get set, eg: [playMenuItem setEnabled:YES];

In awakeFromNib, I also had to tell the menu to setAutoenablesItems: NO. Apparently that’s so I can set their status myself, instead of them being enabled by default if they have a target action associated with them.

Can’t wait to test it when I get home. Just in time for the arrival of the Mac mini!

Anyway, the source and compiled binary can be found here.

I saw a post in the AVS Forums which caught my eye. Well, my iEye, to be precise. It quoted a mention on xlr8yourmac’s daily news from one Graham Jones of Toronto. He was looking for beta testers for his new EyeTV helper app. I wrote to him and told him about my situation.

In particular, my interest was in this feature: “Create aliases to Mpeg files with descriptive file names.”
My thinking was that maybe this could be used with Virtual DVHS. I did some testing and determined that I could not make aliases ending .m2t to actual mpg files in my eyetv library… but I can use softlinks (which is more of a unix, less of a mac, thing).

Contacted Graham with this news. Then I realized (by picking through the source) that unless Virtual DVHS were not open already, it wouldn’t see any new files added to its media folder. So I started hacking on it.

First I made a method that I called TStreamIsKnown, which when passed a ‘stream’ object (a NSMutableArray containing filename, size, last mod date) checks to see if we already know about this stream (eg is it already in our global availTStreams list, which is itself an NSMutableArray.)

Then I added a check to the existing findAllTStreams method, which is what actually looks through the ‘media library’ folder the user specifies, and populates that availTStreams list. (The list is then used to populate the NSTableView called ‘availableTransports.’) The check I made is a call to TStreamIsKnown before adding the stream in question to availTStreams. That way, if findAllTStreams is called again, it’ll skip any files it already knows about, and instead just add the new files it finds (at the bottom of the list. Sorting be darned.)

Next, I added an NSButton, labeled “Refresh”, right above the availableTransports NSTableView, and linked it to a new method refreshFileList, which in turn just calls [self findAllTStreams]; . Then someone suggested that I also add a new NSApplication delegation for applicationDidBecomeActive. So once again, I just linked that to the same method, [self findAllTStreams]; .

Then I just mucked around some more in the Interface Builder and added some hotkey equivalents to menu items like Preferences (cmd-,) and Hide Others (opt-cmd-H) which should’ve had them in the first place.

The last part of this project that I’m embarking on right now would seem (to me, anyway) to be one of the easiest things to do: making the space bar toggle play/pause, and the escape key hit ‘stop.’ This is important to me because when I connect my Mac mini to the DVI input on my TV, I switch to ‘input 5′ to see it. But as soon as I start sending it a transport stream via i.Link (using Virtual DVHS), it ‘takes over’ the screen, much like pressing play on your VCR would cut off whatever channel it was tuned to. Hitting the ‘stop’ button returns you to Input 5… but wait, that’s an issue, because we can’t SEE the stop button in order to click it. And that’s why some keys like play / pause and stop need keyboard equivalents.

But so far I’m having a lot of trouble with it. And once again I’m running into some grey areas of Apple’s HIG: should Full Keyboard Access (something I normally love) interfere with my ability to catch keyDown events? Look at QuickTime Player. It doesn’t appear (to me) to support Full Keyboard Access at all, and spacebar is start/stop in that application. Then look at EyeTV. Yes, it’s kind of a hack, but they just map space to the ‘play’ command in their Controls menu. Wondering if this is what I should do instead.

The advice I’ve gotten so far is that I should subclass either NSApplication (Apple says in their notes that doing this can be a big pain) or NSWindow, so I decided to try subclassing NSWindow. Then I added a call to make it ‘first responder’, which I guess ups its priority in the call chain to receive keyboard events..?

Right now I’m kind of bogged down trying to understand what to actually change in the Interface Builder side of things. I asked a few times in #macdev on freenode, but I’m not feeling like I’m getting very far. Either I’m really close to getting it or I’m going about it all the wrong way.