Virtual Dub 1.5

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Posted on Monday 17th of February, 2003 at 23:31 by SirQUK
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VirtualDub 1.5.0 is out. From the user's prospective, 1.5.0 consists mostly of bug fixes, not the revolutionary change you would expect from a major version bump. The reason for the major bump is that the program has been internally restructured, breaking out some code into libraries and cleaning up the build process significantly. Sources are no longer split across four archives and sylia.dll is no longer statically linked, which should simplify project management a bit.

That is not to say that there are no new features in this release, however. 1.5.0 is the first release to have audio filtering, which has been a requested feature for some time. Now, the audio filtering system is quite rough at this point -- it's not optimized, and the filter selection is a bit sparse. You also cannot write external audio filters yet, although that is definitely going to change. The current selection of audio filters consists mainly of miscellaneous algorithms that I have been playing with for a while within a sandbox WinAmp 2 plugin:

Center cut. The classic "vocal cut" filter, except that the output is stereo instead of mono. This is accomplished through FFT phase analysis; the output will have some warbling in it, but stereo separation is preserved. Also known as the "make your own karaoke to embarrass yourself with" filter.
Ratty phase shift. A time-domain, sawtooth-swept delay line, with rake-like correlation to smooth out the jumps. Good for about +/-20% variation in pitch.

Now, you might ask what a pitch shifter is good for with video. Well, 1.5.0 also contains a stretch filter that allows you to slow down or speed up audio, like a tweaked tape recorder. Combine a stretch and a matched pitch shift, and you get a time stretcher. If you set the pitch shifter and stretcher to the same ratio and tweak the video frame rate to match, you can speed up or slow down video. (Yes, you can now make "Sakura Saku" even faster!) I'm still looking for a better pitch shift algorithm -- the current version has problems with clicking when multiple dominant tones are present. I tried a frequency-domain version once, but it didn't work out too well: frequency-based algorithms don't like sharp attacks and tend to "smear" them, making percussives sound mushy.

Build 15584 (Version 1.5.0): [February 16, 2003]

Features added

Can add a single job to the batch list with syntax: /p[input_file],[output_file]
Filters are now loaded and unloaded on the fly to circumvent TLS (thread local storage) selector limits.
Cropping bounds can now be dragged via the mouse.
Improved, friendlier crash diagnostics.
Basic audio filter support (no plugin support yet, though). The pitch shifter sucks.
Increased accuracy of audio/video timing by switching from microsecond to rational calculations.
Changed font on dialogs to enable ClearType on XP.

Features removed

Deleted outdated 3x3 average filter -- it has been superceded by "blur."

Bug fixes

New MPEG audio core (Priss) -- fixes decoding errors in layer I and layer III audio and adds SSE polyphase support.
Fixed motion JPEG decoding bugs when padding is present before markers.
Fixed crash in SSE2 code when decoding MPEG-1 file odd width in macroblocks.
Fixed crash in SSE2 resize routine when doing 4-tap vertical resample with odd width.
Fixed swapped UVs in About dialog box. ^^;
Fixed sync errors in MPEG-1 playback when decoding an audio stream which flips the copyright bit between frames or switches layer III bitrates (VBR).
Fixed "Frame not found" errors in MPEG-1 decoder when GOP is longer than 128 frames.
Rewrote resampler clip determination code again. Hopefully this one will be Bug Free (tm).
Fixed spurious errors at end of operation when saving WAV file.
Outputted configuration files and job scripts now include the correct audio filename when a .wav file is selected through a script.
Fixed AVI segmented output creating short files when working from MPEG-1 source or when IVTC is active.
Image import filter wasn't caching frames.
Fixed a couple of Get*() script calls that were declared incorrectly internally and didn't work (thanks to Cyrius).
Blur filter now handles cropping properly.