Audio Help.

[Haku]

Got the tcf version of 8 Mile an theres a hum in the background.I was just wondering what filter in cool edit i would have to use to remove the hiss from it.??

Or is there a better program for it?

[BJ_M]

is it a hum (60hz) or a hiss?

if hum use a 60hz notch filter ...

if hiss use a high shelf filter starting at 5000 and reduce by as much as needed till hiss is gone .. but doesnt sound like a phone.

if its generally bad sound -- not a lot you can do .. you can try this which sometimes helps (but may reduce centre channel in the stereo mix to much) ..

load audio into you cooledit .. invert the right channel (there is some setting somewhere im sure) .. save as mono mix down .. .. reload mono and re-save as stereo ... what this does: inverting one channel and mixing together removes all noise that is equal on both channels. if there is more noise on 1 channel than other -- will not work ..
if there is a lot of dialog centered equal on both channels - it will remove a lot of that also .. BUT its possable to save that info also and remix back in knowing that vocal are in the 350 - 3k range centered around 1.2 k up or down depending if male or female or child .. anyway ... i suspect the audio is just crap to begin with and not a lot to be done except filtering selectivly . lot of work ..

[Haku]

I tryed the 60hz notch filter but that didnt work,and i couldnt find the high shelf filter.Maybe its just how its encoded.The speach is clear so u can hear what there saying,its just on the scenes where the just talking quitly or on silence you can hear the hiss/hum more.

[BJ_M]

well that latest info is more informative .. that is a problem of a high noise floor ..

say your normal audio (speech and effects and music) is in the range of

-20 to 0dB for apx 80% of the content and the noise floor is inthe range of -40 .... well for those 20% of the time the main audio drops down in volume to -30 or lower , noise and main audio will be almost at same volume in this example ..

what you need to to do is LOWER the noise floor or in other words increase the distance between the main audio and noise ...

now i dont know how well the audio dub was done on your movie or what levels its at - but normally i would like to see things hover around -6dB for a Dolby encode ..

non the less here is a good explanation on noise reduction in Cooledit:

NOISE REDUCTION

Noise reduction consists of subtracting from an audio signal any constant noise. This background noise can be a fixed frequency like hum. This procedure can be usefull to eliminate 50 or 60 Hz.

On the screen graph of Cool Edit select a portion which does not contain any music or speech, but only hum or hush. You'll need a selection of a few seconds (if possible)
Then in the menu :

Transform
Noise Reduction
Noise Reduction

Default settings :
Snapshots in Profile 100
Reduce by 40 db
Precision Factor 7
Smoothing Amount 1
Transition Width 0 db
FFT Size 6000

Click on Get Profile from selection
Eventually record this profile with Save Profile
Click on Close

Select a musical zone on your graph
And the once again :
Transform
Noise Reduction
Noise Reduction

Select Remove noise
Click on Preview

You should be able to hear the film with noise reduction.
By sliding the Noise reduction level you will be able to change the amount of noise reduction.
Full left : No noise reduction.
Full right : Noise reduction but with effect on the music.
It is up to you to find a "happy medium" and chose the amount by which the "Hush" will be reduced.
Once this is chosen, click on Close and remove any selection that may be still on Cool Edit's graph. Return to Noise Reduction and click on OK to apply to the whole graph.

Hush is a sort of "white noise" containing all the frequencies of the audio spectrum. So noise reduction may have a too great effect on the musical material. If this happens, you will have to change the default settings mentioned above. These settings in fact depend upon the type of content in the musical data.

Another way to evaluate the alteration of the film is to select Keep only Noise before clicking on Preview. This time you will hear the noise removed with also small bits of music sounds. These must not be too loud.

On the two following graphs, one can see the effect of noise reduction on a audio signal;

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HISS REMOVAL

This function removes all frequencies under a given threshold. Signals of a higher level than this threshold will remain untouched. On the other hand, signals under this value will be cut. This threshold, as one could guess, is not a constant, but varies depending upon the frequency.
This methode is also useful for the elimination of hush.

As in the "Noise Reduction" method, one must select a portion the graph that has no music in it, and then,
By the main menu :

Transform
Noise Reduction
Hiss Reduction


Choose one of the settings
Light Hiss Reduction
Standard Hiss Reduction
High Hiss Reduction
depending upon the hiss level.

Click on " Get Noise Floor ". The noise floor appears
( It is possible to modify this curve by pushing the little squares around with the mouse. )

You can than record this curve by Add
Click On Close

Select a representative part of the film on Cool Edit's graph.
Then by the main menu :
Transform
Noise Reduction
Hiss Reduction

Select Remove Hiss
Click on Preview

You should then hear the music with the hiss reduction function.
By sliding Noise Floor adjust , you will apply more or less hiss reduction.
Full Left, no hiss reduction.
Full right, total his reduction, but with musical alteration.
It is up to you to find the right level.
Once found, click on Close and deselect any selection on the graph. Come back to Hiss Reduction, and click on OK.

Another way to evaluate the alteration is to select Keep only Hiss before clicking on Preview. You then hear the hiss that will be removed.

It is up to you to adapt the general settings to your film. The FFT Size seems to be the most important.

the same general principals can be applied to Sonic foundry Sound Forge and also Wavelab (steinburg) and i'm sure other wave editors ..

in terms of great sound editors (software solutions) i would rate the following (in a generalized quality of sound order) i would have to rate Steinberg's Nuendo as best, Logic Audio, wavelab, Protools (software version), Sound Forge , cubase, Reason and Steinberg's Clean (great for getting rid of noise and hiss) and for final mastering and really making your films or projects come alive use T-rackS -24 on the final audio or even existing filsm or your dv and dvd projects ..