hokuto
12th September 2003, 23:26
Below my insert is a snippet I searched for as I had some problems with
DivX files .avi that had hissing, warbling, and just noise!
here' what Dolby does to compensate for tape hiss on cassettes.
You can follow their idea if you know what I mean.
What I did first to getting the hisses out:
1) Open cooledit pro 2.1; open .avi file;
2) highlight hissy area; open up hiss reduction;
3) in hiss reduction use standard hiss preset;
4) press on "Get Noise Floor"
5) press on Help button in Hiss Reduction to get
the meanings of the options for Hiss Reduction.
6) mess with the parameters per Help Section.
7) I was able to get rid of Hiss and keep audio intact.
8) finally use Graphic Eq in Filters to adjust levels
9) Adjust Amplification levels because clipping may occur.
10) use clipping effect to reduce clipping after amplification
because there may still be a few clipped voices here and
there. this is cut and dry but the Help section is very
useful.
Explanation: What I did was not exactly what the doctor
ordered below but imitated to a variance. the key word
being "variance". I did not wish to re-record the entire
47 episodes of GS. So I used some of their intuitive
knowledge. Reducing noise on just about any software
will shape the wave forms and depending on what you did
you may end up with metallic noise (as I have found out)
and end up with a hollow sound or condensed sound.
Also look for Cool Edit Pro Manual on the web using search engine.
THE SNIPPET:
Dolby noise reduction is a two-step process:
Step 1.
When music is being recorded, it is encoded just before reaching the tape. The purpose of encoding is to raise the level of soft, high-frequency passages so they become louder than the tape's noise. During the trip through the Dolby encoder, loud passages (that hide tape hiss) are not altered. Soft, high-frequency passages (that tape hiss affects) are made louder than normal as they are recorded on the tape.
Step 2.
When playing back the tape, the sound is decoded by a precise mirror-image process of the encoding in Step 1. The loud sounds are left unaltered, while the soft, high-frequency sounds are lowered back down to their original levels. (You may have noticed that Dolby B tapes sound brighter when played without any Noise Reduction decoding. Now you know why! You are hearing the encoded sound, not the original.
NOISE REDUCTION TAKES PLACE DURING DECODING. Tape Hiss is added to the recording during the recording process. In step 1 we learned that the Dolby encoder boosted (made louder) the soft, high-frequency passages before the signal reached the tape and before tape hiss was mixed in.
During Step 2, the Dolby decoder doesn't "know," as it scans the signal coming off the tape, that tape noise has been added to the music–it just goes about the business of reducing the encoded sounds to their original levels, with the noise automatically getting the same treatment. The result? Completely restored musical balance but with less hiss in the reproduced sound (see figure 1).
DivX files .avi that had hissing, warbling, and just noise!
here' what Dolby does to compensate for tape hiss on cassettes.
You can follow their idea if you know what I mean.
What I did first to getting the hisses out:
1) Open cooledit pro 2.1; open .avi file;
2) highlight hissy area; open up hiss reduction;
3) in hiss reduction use standard hiss preset;
4) press on "Get Noise Floor"
5) press on Help button in Hiss Reduction to get
the meanings of the options for Hiss Reduction.
6) mess with the parameters per Help Section.
7) I was able to get rid of Hiss and keep audio intact.
8) finally use Graphic Eq in Filters to adjust levels
9) Adjust Amplification levels because clipping may occur.
10) use clipping effect to reduce clipping after amplification
because there may still be a few clipped voices here and
there. this is cut and dry but the Help section is very
useful.
Explanation: What I did was not exactly what the doctor
ordered below but imitated to a variance. the key word
being "variance". I did not wish to re-record the entire
47 episodes of GS. So I used some of their intuitive
knowledge. Reducing noise on just about any software
will shape the wave forms and depending on what you did
you may end up with metallic noise (as I have found out)
and end up with a hollow sound or condensed sound.
Also look for Cool Edit Pro Manual on the web using search engine.
THE SNIPPET:
Dolby noise reduction is a two-step process:
Step 1.
When music is being recorded, it is encoded just before reaching the tape. The purpose of encoding is to raise the level of soft, high-frequency passages so they become louder than the tape's noise. During the trip through the Dolby encoder, loud passages (that hide tape hiss) are not altered. Soft, high-frequency passages (that tape hiss affects) are made louder than normal as they are recorded on the tape.
Step 2.
When playing back the tape, the sound is decoded by a precise mirror-image process of the encoding in Step 1. The loud sounds are left unaltered, while the soft, high-frequency sounds are lowered back down to their original levels. (You may have noticed that Dolby B tapes sound brighter when played without any Noise Reduction decoding. Now you know why! You are hearing the encoded sound, not the original.
NOISE REDUCTION TAKES PLACE DURING DECODING. Tape Hiss is added to the recording during the recording process. In step 1 we learned that the Dolby encoder boosted (made louder) the soft, high-frequency passages before the signal reached the tape and before tape hiss was mixed in.
During Step 2, the Dolby decoder doesn't "know," as it scans the signal coming off the tape, that tape noise has been added to the music–it just goes about the business of reducing the encoded sounds to their original levels, with the noise automatically getting the same treatment. The result? Completely restored musical balance but with less hiss in the reproduced sound (see figure 1).