Pitch correction tool wanted

[clehner]

Can anybody give me a hint if there is a software tool that can do simple real time pitch correction?
I would like to correct the 4% PAL speedup in real time if that is possible. High quality is nice but not an absolute must!

Thanks for any hints.

Regards
Christoph

[castellanos]

If what you have is a wave file, you can easily do it with many audio programs like: Sound Forge, Adobe Audition, Pro Tools etc...
Or, a free way with BeSweet/BeLight: You can convert to NTSC <=> PAL any audio file, even ac3 ones.
Greetings! :)

[clehner]

Castellanos,
thanks for the hint.
However I am not sure whether I was clear what I wanted. I do not want to convert PAL to NTSC or vice versa. I want to correct PAL sound (!) only from an external source, i.e. I have a real time audio stream (2 channel analog in or 5.1 DD) and want to produce a result that is pitch corrected in real time.

[Mug Funky]

ffdshow's audio filter might be able to do this. i can't remember if it has soundtouch (free, very high quality pitch correction tool) built in, but i know it has ac3 output which you'll probably want.

however, "realtime" should be taken with a pinch of salt. there'll be latency at every stage, and the output will probably have quite a delay on it. you should be prepared to delay your video somehow as well. i believe there's units that do this, but i'd need to know your setup.

my 2 cents: you stop noticing the 4% pitch shift pretty quickly. and even if you were to correct the pitch shift, the tempo will still be 4% faster, and this is quite noticable. also, pitch correction leaves you open to artefacts, especially on transients and human voices. soundtouch handles these beautifully (haven't heard an obvious artefact on PAL conformed audio), but even so, somebody who's likely to notice pitch differences will also notice tempo differences. usually it's simpler to just speed the audio up to PAL by assuming a samplerate of 50050, then resampling that to 48000. or in your case you'd be doing the opposite.

[CWR03]

You can still find the Shareware version of Cool Edit 96 via Google search, and it's a very easy-to use tool for that purpose. You will need to convert your audio to .WAV to use it.

[Mug Funky]

hehe, that's hardly realtime though. and the quality of even current versions of cooledit/audition's timestretch is suboptimal.

wavelab apparently has a good one, but i'm not sure if it can be used as a realtime effect either (not really used that program much).

soundtouch should be fine though. works well on speech and transients/impulses.

[odyssey]

*THE* tool for timestretching are Prosoniq Timefactory! It has the best algorithms for time stretching, where Audition (former Cool Edit)'s filters are REALLY bad.

Try for yourself

Unfortunately it's not free, and proberbly quite expensive, but quality costs ;)

[odrazil]

I want to correct PAL sound (!) only from an external source, i.e. I have a real time audio stream (2 channel analog in or 5.1 DD) and want to produce a result that is pitch corrected in real time.

For an analog line-in source, some E-MU audio peripherals (and probably other mid/high-end audio cards) offer real-time pitch shifting.

If your audio is muxed into a media file, an AviSynth wrapper could do what you need.

AviSource("your_video.avi")
# or DirectShowSource("your_mkv_mpg_or_whatever.foo")

TimeStretch(pitch=100*(24000/25025))
# output pitch 95.904095... percent of input pitch
# 24000/1001 = NTSC film frame rate
# (24000/1001) * (1/25) = NTSC rate divided by PAL rate