#60688 - bmnb1234 - Sun Nov 13, 2005 9:26 pm
Hi
I got a question on sound I converted. A dozen sound files a mix of 8 bit and 16 sound files wave and converted them into wave 8 bit 16k files needed for Krawall. I am not experienced in audio so I will try in layman's term The music waves now sound like a old worn out cesset tape. And the have a lot of crackling static is there anyway I can fix this? If so is there a tutorials for audio clueless?
Thank you for your time!
Jason
#60690 - tepples - Sun Nov 13, 2005 10:09 pm
Level compression is your friend. It amplifies the quiet parts of a sample so that when you convert the sample to 8-bit it won't sound as hissy. And even though you have to convert samples to 8-bit, I don't see a reason why you have to convert them to 16 kHz unless you're using them for sound effects.
Could you post a copy of the .s3m or .xm file before and after conversion so that I could look at it in Modplug to see what you did wrong in the conversion?
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#60867 - thegamefreak0134 - Tue Nov 15, 2005 5:45 pm
Krawall mixes at 16k, so I can see why you might think you need do downgrade your samples. However, if you have for instance a sample playing at half speed, (an octave lower) the extra quality actually improves the overall sound. Higher samples don't usually tend to suffer, but lower samples benefit from higher quality.
I hear tell that converting from 16 bit to 8 bit adds a lot of noise. You might try if possible creating your samples in 8 bit rather than converting down to it.
Are your cracks and pops at the louder parts of the samples? Your samples may be too loud. You might also have too many loud samples playing at once. (remember that in mixing, you ADD samples together...) Be careful of this.
If I'm wrong on any of this, let me know. I only just recently got krawall working for me.
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#60922 - tepples - Wed Nov 16, 2005 2:58 am
thegamefreak0134 wrote: |
I hear tell that converting from 16 bit to 8 bit adds a lot of noise. You might try if possible creating your samples in 8 bit rather than converting down to it. |
Actually, it's better to create in 16 bit and then truncate or dither to 8 bit because it introduces less noise along the way.
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#60955 - keldon - Wed Nov 16, 2005 9:19 am
truncating doesn't do much and it sounds awful because what you are actually doing is performing (a = a >> 8). Any sound which falls inbetween is going to suffer.
Also perform a low pass filter, or EQ down the high end a little before dithering
#61029 - thegamefreak0134 - Wed Nov 16, 2005 9:29 pm
These are terms I've never heard of before. What do they mean? Are they compression terms?
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#61030 - keldon - Wed Nov 16, 2005 10:13 pm
dithering is exactly what you do in graphics; basically it allows the same amount of detail to be portrayed with less colours - or in the case of music, bits.
It is achieved by applying noise to the image (/audio sample) before downsampling - causing the dithering effect. Not applying dithering in audio has the exactly same effect it has in graphics - but it sounds much worse than it looks. Truncating the bits is equivalent to simply turning down the amount of colours your pictures has in mspaint
Low pass filters smooth out images (and audio). In images low pass filters give the image a blurred effect - in audio it makes high frequency sounds quiter and some disappear. Applying low pass and dither before downsampling produces better results in both images and audio
The low pass is to counter lowering the sample rate .... and dithering is to counter using less bits
---- an example of dithering
original audio sample: 0123456789876543210
reduction to 3 numbers(truncating):0003336666666333000
with dithering: 030336366666363303000
The effect of dithering has the wave jumping between near numbers instead of of flattening them out. Your ears then reproduce a slope inbetween .... it's just the same thing as when you have a dithered image where your eyes percieve dithered colours as a single (though textured) tone.
#61038 - ScottLininger - Thu Nov 17, 2005 12:55 am
There's a freeware sound editor out there called Audacity that includes a noise-removal filter that isn't half bad. I've been able to rescue a few sounds that were "hissy" by using it.
-Scott
#61224 - bmnb1234 - Fri Nov 18, 2005 1:43 am
thanks I will give a try!
#61879 - yannis - Thu Nov 24, 2005 2:39 pm
I've never used dithering. I find dithering adds extra noise where you don't need it.
There's a few techniques I use to get perfect 8 bit samples.
1) EQ
2) Hard Limiting + Volume Maximization
3) Specially created noise reduction signature
Firstly having a clean sample is what you need first off. No background noise, when you compress or heavy limit you bring up the noise level. This is different than 8bit noise created by low levels but makes for a less crisp sample.
If you want to send me a sample to convert, I can give it a look at and let you know if it's good quality enough to convert to 8bit 16kHz.
email me: info@groovyaudio.com
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