sample playback doc

[fred76]

Is there any good document on how to playback samples in 68k?
I'm new at this technique so I don't know anything and a beginner's guide would be really helpful.

[simonsunnyboy]

Ray / TSCC has a sample source on his webpage. however he entirely omits how to program a Timer interrupt properly (which can be a problem for the newcomer).

[Mug UK]

I've got some source code somewhere from a sampled demo - will upload it later on tonight if still needed.

[fred76]

I've got some source code somewhere from a sampled demo - will upload it later on tonight if still needed.

Any demo/help is welcome.

[Mug UK]

Several pages to help you out:

Ray's 16/32 bits - http://freenet-homepage.de/ray.tscc/samples.htm (also has a link to An Cool's page at http://home.earthlink.net/~chhome/tcbtracker.html)

And this attachment (open it up in STEEM and copy the files onto your virtual STEEM h/drive to make them easier to read on your PC/MAC) is a simple guide to demo coding by James Ingram and includes sample replay on a stock ST and STE machine.

[fred76]

This is very good stuff to start with. James Ingram rules !
And so do you guys...
Thanks

[fred76]

Another question, since I need AVR format.
My copy of 525 (v211) seems to hang whenever I try to convert samples.
Is this a known problem ?
Do I need another program ?

[Mug UK]

Use Soundlab instead?

[fred76]

Soundlab only seems to work from Drive A (or B), not from harddisk.
I'll try to find a windows convertor.
Any more suggestions ?
What do you guys use to convert ?

[simonsunnyboy]

I had good success with 525 i the past...this converts many sound sampel formats to others.
It might be a tad slow on a plain ST (or even standard Falcon) but it is pretty straight forward to use.

[Mug UK]

Soundlab only seems to work from Drive A (or B), not from harddisk.
I'll try to find a windows convertor.
Any more suggestions ?
What do you guys use to convert ?

Strange as that's a copy RAR'd up from my emulated STEEM drive C:

[fred76]

It works fine under Steem ! 525 also works fine under Steem.
I'll never use WinSTon again !
I also wrote a little program that converts raw pcm 8 bits to AVR.
runs under windows.
If anyone might be interested I will post it as soon as I polished it.

[Mug UK]

The muso's on here would love a batch tool that downsamples stereo 44Khz WAV or MP3 samples into single channel 8-bit raw samples

Had to do them a folder at a time when I converted a few for Marcer last year .. would be nice to point a tool like above at a folder and say "off you go" and it converts the lot!

[nativ]

Hi,
Aniplayer will load MP3 and save Avr.
If I recall . . . .

Thanks

[bod/STAX]

I used to use a program called NoiseMaster on the PC. You can resample your samples into any frequency,
which is ideal for convertivng .WAV files to your ST. If you do a quick Google search you can find a few
programs to convert MP3's to .WAV.

Here's the program, along with the source code to the Megabang demo for replaying samples on the ST:

[fred76]

Nice demo. Looked into the code and can really learn from it as it uses MFP.
Might crash the ST a thousand times by trying, just like the good old days.

The muso's on here would love a batch tool that downsamples stereo 44Khz WAV or MP3 samples into single channel 8-bit raw samples
.. would be nice to point a tool like above at a folder and say "off you go" and it converts the lot!

If you have a nice algorithm for 44k1 16-bit WAV to 8-bit whatever freq.(<30k) I will think about it.
...Actually, I am thinking about it. Would be a nice tool !

[unseenmenace]

I don't know if you started a conversion tool but a fast and simple method would be the following:-

Convert from 16-bit to 8-bit by discarding the least significant 8 bits (i.e. just take the most significant byte).
Then reduce to simple fractions like 3/4, 2/3, 1/2, 1/3 or 1/4 frequency by skipping bytes or taking averages of each few bytes.
Its worth noting that 1/3 of 44.1KHz (CD playback frequency) is a little under 15KHz which is the frequency you get if you synchronise sample playback with scanline redraw (At 50Hz/PAL) which is useful if you want to play samples alonside rasters/plasmas/fullscreens etc.
You may want to convert to unsigned format as this is best for playback via the ST's YM2149 sound chip. I believe this is just a case of adding 128 to each signed byte.

[ppera]

...
Convert from 16-bit to 8-bit by discarding the least significant 8 bits (i.e. just take the most significant byte).
Then reduce to simple fractions like 3/4, 2/3, 1/2, 1/3 or 1/4 frequency by skipping bytes or taking averages of each few bytes.
Its worth noting that 1/3 of 44.1KHz (CD playback frequency) is a little under 15KHz which is the frequency you get if you synchronise sample playback with scanline redraw (At 50Hz/PAL) which is useful if you want to play samples alonside rasters/plasmas/fullscreens etc.
You may want to convert to unsigned format as this is best for playback via the ST's YM2149 sound chip. I believe this is just a case of adding 128 to each signed byte.

I tried with averaging in sample playback of 25033 KHz signed sample (for STE), for playback via YM (PSG) with half sample rate. So, averaged 2 neighbout values and sent result to lookup table. But sound was very bad. It is unexpected, I think. Don't know reason, really. Lookup table is for signed values (probably there are for non-signed too).
Hmm... maybe averaging signed value is not same as non-signed ? 50 + 80 = 130 . /2 =65 average. In signed values it would be: 178+208=386. 386/2=193. 193-128=65 . Matches. So theory and practice is not same here.... Or I made some dumb bug in simple rutine ?

[oberje]

For 2:1 downsampling, you're better off just dropping the extra samples. Ideally you'd first pass the sample through a filter to band-limit it, but that's not viable on an ST in realtime!

If you're still looking for a good batch process to downconvert wavs to ST playback ranges, on the PC, sox is a good bet, it does decent resampling.

Cheers,
oberje