06-14-11 - ProcessSuicide

The god damn lagarith DLL has some crash in its shutdown, so any time I play an AVI with app that uses lagarith, it hangs on exit.

(this is one of the reasons that I need to write my own lossless video format; the other reason is that lagarith can't play back at 30 fps even on ridiculously fast modern machines; and the other standard HuffYUV frequently crashes for me and is very hard to make support RGB correctly)

Anyhoo, I started using this to shut down my app, which doesn't have the stupid "wait forever for hung DLL's to unload" problem :

void ProcessSuicide()
    DWORD myPID = GetCurrentProcessId();

    lprintf("ProcessSuicide PID : %d\n",myPID);

    HANDLE hProcess = OpenProcess (PROCESS_ALL_ACCESS, FALSE, myPID); 
    if ( hProcess == INVALID_HANDLE_VALUE )
        lprintf("Couldn't open my own process!\n");
        // ?? should probably do something else here, but never happens
    // ... ?? ... should not get here
    CloseHandle (hProcess);

At first I thought this was a horrible hack, but I've been using it for months now and it doesn't cause any problems, so I'm sort of tempted to call it not a hack but rather just a nice way to quit your app in Windows and not ever get that stupid thing where an app hangs in shutdown (which is a common problem for big apps like MSDev and Firefox).


Anonymous said...

The UT Video codec is thankfully much faster with only 5-15% worse compression. You are essentially limited to your I/O with UT. It has some bugs as well but I use it several times a week for a commercial product. Here's a thread with download links for v8.5.2 and v9.0.0: http://forum.doom9.org/showthread.php?t=143624&page=10

jfb said...

I do this with ExitProcess(0) for my Mono programs. Their issue is that if you let it do a normal .Net 'exit', it tries to garbage collect or call finalizers or whatnot (who cares, really? It's exiting, I don't need to free memory first...), and often deadlocks.

It might be a "hack", but it's better than spending a lot of work on exiting when a modern OS can clean it up anyway. :) Especially when you don't control all the problem libraries...

cbloom said...

Bloody Blogger marked trixter's comment as spam. It is not spam, it's awesome!

UT is in fact totally functional. And I love that he exposes the different formats (RGB,RGBA,YV12,etc) as different 4CC's (rather than a flag inside the format) - it makes it so much easier to just pick the right one.

cbloom said...

What's more, UT can actually play back video at full speed! Yay!

And the source code is really nice and clean.

cbloom said...

Ah.. interesting. UT is a huffman-DPCM sort of like PNG. The predictor he uses is a form of "clamped gradient" which I wrote about before. It's a very good predictor and is uniformly good so it means you can write optimized assembly just for that one, rather than having to support a whole bunch of predictors.

On encode, his code to form the delta from prediction is very good, SSE that does 16 bytes at a time. But then accumulating the huffman counts for the deltas is not awesome.

On decode, he does one byte at a time using lots of cmovs or MMX pmin/pmax. This is an unfortunate necessity due to left-neighbor serialization.

A north-neighbor only predictor could be much faster but is also a worse predictor.

An LZ back end should get more compression and also be faster than a huffman-only back end.

Even a super-simplified LZ that only does 16-byte matches or something like that might help.

Anonymous said...

If you're going to write your own lossless codec - thumbs up. This area is seriously underdeveloped.

old rants