AC3 or MP3 noise reduction filter

[Moti172]

Hi

I tried to encode old movie's AC3 soundtruck to MP3.
There's a "BAZZZ" noise from the begining of the soundtruck, and I wonder is there any noise reduction filter that can minimize that.

I'm using Azid 1.9 and lame

Thanks

[setarip_old]

Hi!

You should be able to accomplish that by using an audio editor such as (commercial) GoldWave or (freeware) Audacity...

[Sunhillow]

but you should
1. decode to wav
2. apply any filters
3. encode to mp3

so you avoid multiple re-encoding with lossy formats

[Moti172]

Thank you for the advise
I'll give it a try

[Sharktooth]

i would like to know if there's an avisynth filter for audio that does some noise reduction and maybe other filtering.

[Mug Funky]

search for "soxfilter"...

seems pretty useful, but i can't make its companders work for me the way i want :(

there's a huge number of filters you can invoke though, including noise reduction i think.

[edit]

on the ac3 noise reduction:

sometimes hiss or buzz or loud pilot tones that we'd want to filter out have been used by the codec as "maskers". this means that when you remove these noises, you might discover the audio underneath sounds highly compressed, because the encoder has decided to give less bits to those parts due to masking from the sound you want to remove... usually it's not that extreme and it's definitely worth removing annoying noises.

with ac3 it's probably not an issue, but ex mp2 or mp3 stuff can really bite you with hidden artefacts when you remove stuff.