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Old 07 November 2015, 20:27   #1
dissident
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WAV-16-bit-files converted to RAW-8-bit-files

I'm planning to compose some protracker-MODs with the Roland TR808 samples.

I have found the right WAV-samples in 16 bit format and converted them with wav2ami into RAW-8-Bit files to use them with the protracker. I know that the quality decreases converting 16 bit to 8 bit.

But the result in most cases is horrible. Much noise superimpose the samples data and the amplitude is very low so the samples are not very loud. The highhat/handclap/ claves samples on the ST-01: are much better than the converted ones from the WAV-files.

Reworking the samples (cutting the length etc.) with the protracker didn't help very much.

Does anyone know a better way or a tool for converting without decreasing the quality so much?
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Old 07 November 2015, 21:18   #2
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Quote:
Originally Posted by dissident View Post
the amplitude is very low so the samples are not very loud.
That's part of the problem. The 16 bit samples have to be as loud as possible without clipping before you convert them to 8 bit. For use in Protracker they also have to be down sampled using a good down sampling algorithm. Also, DO NOT USE DITHERING! The sample rates will be way to low for dithering to be useful.

There may be a bit more to it than that. Some of our local audio experts will probably explain this better than I can
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Old 09 November 2015, 23:17   #3
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That's part of the problem. The 16 bit samples have to be as loud as possible without clipping before you convert them to 8 bit.
Thanks for the hints. Working with Audacity I changed the volume to the maximum before the converting.

Quote:
For use in Protracker they also have to be down sampled using a good down sampling algorithm.
It seems that wav2ami already samples down and only works with 16 bit. Reducing the sample rate to 8 kHz and the depth to 8 bit in Audacity before saving didn't work. Strange effects with messed up data were the result of the wav2ami converting.
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Old 09 November 2015, 23:48   #4
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You can use the script in there (check the entire post)
http://eab.abime.net/showpost.php?p=940131&postcount=3

it will apply some compression to enhance the lost of resolution. You can modify the script to match your requirements
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Old 17 November 2015, 19:12   #5
dissident
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Originally Posted by adrdesign View Post
You can use the script in there (check the entire post)
http://eab.abime.net/showpost.php?p=940131&postcount=3

it will apply some compression to enhance the lost of resolution. You can modify the script to match your requirements
Great, that helped me a lot. Now the converting of the 16-bit samples has a much better result of 8-bit samples. Many thanks adrdeign
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Old 22 March 2016, 05:10   #6
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I came across this thread, and also noticed that wav2ami automatically down samples, as opposed to e.g. sox. I need to down sample, otherwise the pitch is too low for use in Protracker. Can someone explain why that is, why I need to down sample?
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Old 02 April 2016, 22:57   #7
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because original samples are probably at 44.1khz... and Amiga will play at some much lower rate
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Old 04 April 2016, 17:12   #8
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Side to this adrdesign script is incorrect as Amiga (Paula) have no 22050Hz sample rate.
Closest to 22050Hz is AUDxPER=161 and frequency 22030Hz (real 22030.4Hz).

It is easier to perform conversion on PC, bellow verified sox syntax:

(stereo is converted to mono, sample rate conversion to 22030Hz, automatic gain to maximize level without clipping)

Code:
@sox --multi-threaded --buffer 65536 -S -V -D %1 -e signed-integer -b 8 -c 1 %~n1.s8 remix - rate -v -s -L 22030 gain -n -0.07 stats -b 8 stat
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Old 04 April 2016, 18:01   #9
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If you play a 22050Hz sample in protracker 22168Hz or 22030Hz I don`t see/hear any problem. You get problems when your sample is a drumloop (at least 4 beats). Then it can go out of sync. I also noticed that BPM might be different from device to device. For example when I record a drumloop at 125 BPM from MC-303 and play it in Protracker at 125 BPM it needs finetuning to fit the sync.

However, for single instruments and most non drumloop samples a simple 44,1kHz to 22050Hz conversion is good enough IMO. Drift errors can be fixed by finetuning.
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Old 05 April 2016, 19:59   #10
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Originally Posted by daxb View Post
If you play a 22050Hz sample in protracker 22168Hz or 22030Hz I don`t see/hear any problem. You get problems when your sample is a drumloop (at least 4 beats). Then it can go out of sync. I also noticed that BPM might be different from device to device. For example when I record a drumloop at 125 BPM from MC-303 and play it in Protracker at 125 BPM it needs finetuning to fit the sync.

However, for single instruments and most non drumloop samples a simple 44,1kHz to 22050Hz conversion is good enough IMO. Drift errors can be fixed by finetuning.
I'm not a musician but even at this forum there are discussions about musical notation, frequencies etc where 20Hz detune seem to be big issue.
Playing 22050Hz transposed down by almost 20Hz seem to me like not the best idea especially in case where people complain that Amiga sample rate are not in line with common musical notation, and yes - i agree probably 20Hz detune will be not particularly noticeable by most of people but if things can be done correctly then why bother especially that proper sample rate conversion take on PC anyway less time than on Amiga (from my perspective modern PC with lot of RAM, CPU power, and storage space is better tool to convert from 16 bit to 8 bit than Amiga - also amount of data required to transfer is lower).
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Old 05 April 2016, 21:44   #11
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If 22050 isn't correct, let's not use it! 20Hz could be a problem and finetuning within Protracker isn't the best option.

Then again it isn't all that simple. Supposedly, if you are converting samples in different keys, you need to use different sample rates.

The "one for all" method only works if you are going to use Protracker just for sample sequencing, meaning you aren't going to "compose" there or you convert every asset on the same key to the same sample rate. The moment you introduce a sample from another source, you're gonna hear the problems.
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Old 06 April 2016, 12:40   #12
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Quote:
Originally Posted by Akira View Post
If 22050 isn't correct, let's not use it! 20Hz could be a problem and finetuning within Protracker isn't the best option.

Then again it isn't all that simple. Supposedly, if you are converting samples in different keys, you need to use different sample rates.

The "one for all" method only works if you are going to use Protracker just for sample sequencing, meaning you aren't going to "compose" there or you convert every asset on the same key to the same sample rate. The moment you introduce a sample from another source, you're gonna hear the problems.
Well, my point was only related to 22050Hz vs 22030.4Hz on Amiga.
All above are valid and i believe this is well known limitation for wavetable samplers.
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