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Subject: Re: Playback Speed/Pitch

Re: Playback Speed/Pitch

From: Dominik Riebeling <>
Date: Sat, 6 Jan 2007 09:54:10 +0100

On 1/6/07, Alexandre Enkerli <> wrote:
> Is there any way to increase playback speed (without changing pitch) by more
> than 2%? If not, is it a hardware limitation?

It is NOT possible to change the playback speed without affecting the
pitch (i.e. timestretching) at all. There is no 2% time stretching
feature in Rockbox, so please stop talking about.

> podcasts and audiobooks a completely different experience. If it weren't for
> the 2% limitation, it'd be easy to sell Rockbox devices as the ideal
> podcast-listening tool (what with bookmarking, etc.).

Rockbox is an open source project. It's not a product planned in any
way to sell. If you like it feel free to donate some money to the
project. So thinking about what would make it better selling is
completely useless and of no interests to the Rockbox team.

There is not 2% limitation. The 2% thing is for beat matching and for
that reason the 2% steps don't stick. It is NOT timestretching. It
also has the "chipmunk" thing (which might be not that easy to hear at

> (Using a mid-December Rockbox build on an iRiver H120.)

When reporting things please make sure to use a current build. Rockbox
changes pretty fast (at least sometimes), so reporting against a one
week old build may already be outdated because someone might already
have implemented / fixed the issue.

As for your question: real timestretching is a lot more cpu intensive
than pitching (read: faster playback like Rockbox currently does) and
nobody has implemented it yet. Feel free to work on it yourself and
submit a patch. We have feature requests for time stretching (faster
playback without changing the height of the music tones) and the
opposite, changing the music tones without affecting the playback
speed. I'm pretty sure a lot of people would love such a thing.

 - Dominik
Received on 2007-01-06

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