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Subject: Rockbox accessibility + suggestions for audio tempo change (time-stretch, no pitch change)

Rockbox accessibility + suggestions for audio tempo change (time-stretch, no pitch change)

From: Daniel Weck <>
Date: Tue, 8 May 2007 23:38:19 +0100

Hi all !

The Gigabeat F/X seems to provide enough horse-power to run complex
audio algorithms (ARM9 300 MHz).

In addition to the self-voicing / TTS user-interface already
available in Rockbox, the ability to change the audio tempo (without
changing the pitch, aka "time-stretch") would be great, especially
for blind / visually impaired users who tend to listen to speech at
much higher rates.

I know of at least 3 real-time C/C++ implementations (open-source), I
am sure they could easily be ported to Rockbox:

1) "MFFM WSOLA TimeScale", by Matt Flax

I am not sure the above website is up-to-date. The latest code can be
found in the "AMIS" Daisy player (Digital Talking books):

2) "TPBReader / Vupp", by TPB

The above website does not contain the source code, but incidentally
the "AMIS" player also integrates this audio algorithm:

3) "Soundtouch"

I actually have no experience of real-time audio modification with
this implementation. It is used in Audacity for "off-line" audio
transformation, I think the lowest quality can run in real-time mode.

Ideally, Rockbox could also read Daisy content (Accessible Digital
Talking Books). This would provide powerful navigation features for
all users, not just the blind and visually impaired. What level of
support does Rockbox have for XML ?

Let me know what you think.
Regards, Daniel.
Received on 2007-05-09

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