vs1003b pitch/tempo shifting

Writing software for systems that use VLSI Solution's devices as slave codecs to a host microcontroller.
Cocoa
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Re: vs1003b pitch/tempo shifting

Post by Cocoa » Wed 2020-11-18 5:29

It's a mp3 file. Sample rate=44.1khz. Bitrate=128kbps.
Clock=12.288MHz, CLOCKF=0xf800, SPI_MODE=0x0804.
Attachments
using algorithm (normal speed).m4a
(408.99 KiB) Downloaded 7 times
using algorithm (1.5×normal speed).m4a
(1 MiB) Downloaded 10 times
using algorithm (1.2×normal speed).m4a
(1.3 MiB) Downloaded 9 times
using algorithm (0.99×normal speed).m4a
(847.07 KiB) Downloaded 10 times
using algorithm (0.9×normal speed).m4a
(865.33 KiB) Downloaded 10 times
using algorithm (0.8×normal speed).m4a
(693.24 KiB) Downloaded 10 times

Cocoa
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Re: vs1003b pitch/tempo shifting

Post by Cocoa » Wed 2020-11-18 6:57

It confuses me a lot that speed-down playing is worse than speed-up playing, that's really amazing.
Here is the original song.
Attachments
Original song.mp3
(4.61 MiB) Downloaded 8 times

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pasi
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Re: vs1003b pitch/tempo shifting

Post by pasi » Wed 2020-11-18 10:43

It sounds like that's what that specific algorithm can accomplish.

The difference between speeding up and slowing down is that when speeding up, the playback plays everything only once (uses windowing to play two portions at the same time to "compress" the playing time), while when slowing down the playback needs to play some portions of the output twice.

Although slowing down also uses windowing, it won't sound as good, because for example you'll get transients twice if they appear in the windowed portions. When speeding up any transients only appear once, although their order might sometimes be swapped.

We have some better approaches, but they are not for vs1003.
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Cocoa
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Re: vs1003b pitch/tempo shifting

Post by Cocoa » Wed 2020-11-18 11:53

Thanks for your explanation. By the way, which of your products are capable of performing it well ? What are them ? :D

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pasi
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Re: vs1003b pitch/tempo shifting

Post by pasi » Wed 2020-11-18 14:30

A better version of the pitch shifter is available for VS1005.

The original version: http://www.vsdsp-forum.com/phpbb/viewto ... =13&t=2092
And later integrated into the regular distribution (see the link in the second post of that thread).
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Cocoa
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Posts: 9
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Re: vs1003b pitch/tempo shifting

Post by Cocoa » Thu 2020-11-19 11:33

Thanks a lot, Pasi !

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