[raspberry-vi] Welcome new joiners and progress with audio latency
- From: Mike Ray <mike@xxxxxxxxxxxxxxx>
- To: raspberry-vi@xxxxxxxxxxxxx
- Date: Mon, 06 Jan 2014 12:25:32 +0000
Hello list,
We have a couple more joiners. So welcome to them. Please feel free to
give us an intro if you haven't posted yet.
The list can often be pretty quiet, with flurries of activity now and again.
Audio latency...
I have made some progress on finding a solution to the audio latency
problems which plague us on text-to-speech, which in turn affects
screen-readers etc.
I have spent the last four days, and lots of the dark hours as well,
getting to grips with pulseaudio.
Up to now we have tried using espeak in it's default form, which uses
the portaudio system. It is this which is suffering latency problems
and causing tts to stutter very badly and also to cause a kernel oops at
regular but random points.
When I re-compile espeak to use pulseaudio instead of portaudio, the
stuttering is totally gone.
Now I need to test Emacspeak and see if I can get SpeakUp and Emacspeak
running side-by-side. And it is looking good.
I've been all round the houses with pulseaudio, and like so many things
I have spent hours trying to understand how it all works and can now
have it up and running in about ten minutes.
Also, those who have been here for a while and have been following this
thread will remember there was a problem with the previous version of
our accessible Arch Linux image not booting on Pi boards equipped with
'Hynix' RAM chips.
And the audio problems meant that we had to blacklist the kernel and
firmware updates. This locked us into kernel and firmware versions
which were pre-April 2013.
I'm pleased to say that the current image I am working on is totally up
to date and is using kernel version 3.10.25, which is the latest Pi
kernel version.
So, in brief:
1. pulseaudio seems to be solving the tts problems.
2. The latest kernel and firmware will mean Hynix boards will boot.
If I can't get Emacspeak to run alongside SpeakUp initially, I will
release an image with just SpeakUp because I know some are waiting for
this and are not that bothered about Emacspeak.
Assuming this fixes the kernel oops, I will then go back to Raspbian and
see if I can get SpeakUp to run on there with no crashes.
I am not sure whether the Foundation's introduction of the 'Newbs' thing
makes the latest Raspbian even less accessible because I think there is
another menu to go through to select an operating system.
Mike
--
Michael A. Ray
Analyst/Programmer
Witley, Surrey, South-east UK
I KEEP six honest serving-men, They taught me all I know. Their names are What
and Why and When and How and Where and Who.
-- Rudyard Kipling (paraphrased)
Interested in accessibility on the Raspberry Pi?
Visit: http://www.raspberryvi.org/
From where you can join our mailing list for visually-impaired Pi hackers
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Mike Ray, list creator, January 2013
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