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AKA :
Variable Offset Amplitude
Credits :
| Code | .... | Algorithm of Algotech, Onslaught, svenonacid |
| Graphics | .... | Algorithm of Algotech, Onslaught, svenonacid |
| Design | .... | Algorithm of Algotech, Onslaught, svenonacid |
| Charset | .... | B-Wyze of Hardcore, Onslaught, Success |
| Concept | .... | Algorithm of Algotech, Onslaught, svenonacid |
| Loader | .... | Krill of Plush |
| Sampling | .... | Algorithm of Algotech, Onslaught, svenonacid |
Download :
Look for downloads on external sites:
Pokefinder.org
Summary
Submitted by algorithm on 12 August 2014
Demonstrates the output of my pc encoder that is able to convert full 3 minute audio tracks into a single disk side for playback on a c64.
It is a huge improvement over VQ based methods as it freely allows sliding references into the 4k wavetable instead
of being snapped to chunks (8,16 etc)
Furthermore for quality increase, each chunks amplitude can be updated to 1 of
16 volume levels.
This allows a total of over 65000 16 byte chunks that can be recreated by only a 4k wavetable
This particular example compresses each 16 byte sample into two bytes which consist of a 12bit value for the offset into the wavetable and 4bits of amplitude.
I could have created the full decode via nmi and to reconstruct the next set of 16 bytes (or prepare offset/amplitude) while the previous 16 is being read, but this first implementation worked and left it at that
The oscilliscope effect is rather basic and updates sprite y pointers after each 16 byte chunk has been decoded into the buffers. Per line update could have been possible, but most of the code had been finished already and did not recode the demo.
The demonstration utilises the filter based d418 method, hence quality may vary on machine to machine, however autodetect is used in the demo in order to try and ensure that quality does not suffer between the two sid models.
The example tune has many repeating sections, however this encode method works well for any type of audio including audio with no repeating sections.
Quality can be increased further via multiple offsets and mixing (infact i have already created encoders that can mix 4 chunks with amplitude) To be implemented in a future demo
Disk is 40 tracks. |
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8.8/10 (15 votes) 