timidity-talk

[timidity-talk] Strange glitch at start of default instrument (piano)'s output

[Martin G. <mar...@gm...>]

Hi and thanks for timidity, a truly wonderful program.

I'm writing because the Timidity bug tracker, like all the release
notes, seem to be down.

Here's the bug I am seeing:

Whenever I synthesize a MIDI piece using the default instrument, Grand
Piano, I get a series of random spikes in the first half second of the
right channel of the output - between 6 and 9 random samples at
seeming random moments, which sound like a harsh crackle. After these,
for the rest of the piece, everything plays perfectly.

This is on Ubuntu 16.04 (the current stable release, with Timidity
2.13.2) but has been happening since 2012 for sure.

Here is a minimal example of a single MIDI note, synthesized to a WAV

martin@score:~/audio/D-D/scores$ timidity -Ow -o note.wav note.mid
Playing note.mid
MIDI file: note.mid
Format: 1  Tracks: 2  Divisions: 480
Copyright: Copyright (c) xxxx Copyright Holder
Cue point: Created by Rosegarden
Cue point: http://www.rosegardenmusic.com/
Track name:
Playing time: ~4 seconds
Notes cut: 0
Notes lost totally: 0

The sound is the same when playing directly to the audio output.

I attach midi input and pictures of output, as well as a waveform view of the
whole noise phenomenon and a zoom of one-pixel-per-sample of the first
one. The wav file (400k) is at http://martinwguy.co.uk/test/note.wav

Am I the only one seeing/hearing this effect?

    M

Re: [timidity-talk] Strange glitch at start of default instrument (piano)'s output

[Martin G. <mar...@gm...>]

On 30/05/2016, Matthew wrote:
>On 29/05/2016, Martin Guy <mar...@gm...> wrote:
>> Whenever I synthesize a MIDI piece using the default instrument, Grand
>> Piano, I get a series of random spikes in the first half second of the
>> right channel of the output - between 6 and 9 random samples at
>> seeming random moments, which sound like a harsh crackle. After these,
>> for the rest of the piece, everything plays perfectly.
>>
>> This is on Ubuntu 16.04 (the current stable release, with Timidity
>> 2.13.2) but has been happening since 2012 for sure.
>
> Yes, unfortunately it's been like that for ages.  The workaround is to
> specify --output-24bit.

It seems to be fixed in 2.14.0

Thanks!

    M

Re: [timidity-talk] Strange glitch at start of default instrument (piano)'s output

[Martin G. <mar...@gm...>]

> On 30/05/2016, Matthew wrote:
>>.  The workaround is to
>> specify --output-24bit.

The bug report is https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=693011
and it was introduced with the new noise-shaping code.
It suggests a less invasive workaround to make it use the old noise shaper:
    --noise-shaping=1

On 30/05/2016, Matthew wrote:
> That's great - still on Ubuntu 14.04 and it's still 2.13.2.

I've applied the bug fix to the Ubuntu source code; you'll find the
fixed package(s) under
    http://martinwguy.co.uk/test
It is probably enough to fetch and install
    timidity_2.13.2-40.3+nocrackle_amd64.deb (64-bit)
or
    timidity_2.13.2-40.3+nocrackle_i386.deb (32-bit)

I've also submitted a bug report to Ubuntu
    https://bugs.launchpad.net/ubuntu/+source/timidity/+bug/1587215
so let's hope they apply the fix retroactively as part of the maintenance;
If they do, their 2.13.2-40.4 will replace the above packages.

Thanks for your help in resolving this issue

    M