22 Jan
2011
22 Jan
'11
3:25 a.m.
when I connect the output of Audacity to Timemachine _by hand_ using
Patchage
there is a delay in the stereo sound file between the start of audio in
ch1 & 2
which is equal to the time at which the connections are physically made
to timemachine
in other words:
- I create a 10 sec file of 440Hz sine in Audacity
- play it back on loop
- go to Patchage and connect ch1 from PortAudio (which is actually
Audacity) to Timemachine wait 10 seconds then connect ch2 to the other
input of Timemachine
- hit record on Timemachine wait a couple of seconds
- stop record on Timemachine
- stop playback of 440 sine in Audacity
- open the sound file recorded by Timemachine in Audacity
- look at the start of the sound file
- there is a delay between channels seen in the sound file equal to the
time I waited to connect ch1 & ch2
side question: why do the outputs of Audacity appear as PortAudio in Jack?
is it a reference to virtual ports being instantiated when playback
occurs in Audacity?
22 Jan
22 Jan
9:36 a.m.
On Fri, 2011-01-21 at 18:25 -0800, Kim Cascone wrote:
when I connect the output of Audacity to Timemachine
_by hand_ using
Patchage
there is a delay in the stereo sound file between the start of audio in
ch1 & 2
which is equal to the time at which the connections are physically made
to timemachine
in other words:
- I create a 10 sec file of 440Hz sine in Audacity
- play it back on loop
- go to Patchage and connect ch1 from PortAudio (which is actually
Audacity) to Timemachine wait 10 seconds then connect ch2 to the other
input of Timemachine
- hit record on Timemachine wait a couple of seconds
- stop record on Timemachine
- stop playback of 440 sine in Audacity
- open the sound file recorded by Timemachine in Audacity
- look at the start of the sound file
- there is a delay between channels seen in the sound file equal to the
time I waited to connect ch1 & ch2
Maybe you could try with a JACK-native audio player. See below...
side question: why do the outputs of Audacity appear
as PortAudio in Jack?
is it a reference to virtual ports being instantiated when playback
occurs in Audacity?
No, it's because Audacity does not support JACK. It only half-manages it
through using the PortAudio library.
Peter.
11:38 a.m.
On Sat, 22 Jan 2011 08:37:04 +0000
Peter Nelson <peter(a)fuzzle.org> wrote:
On Fri, 2011-01-21 at 18:25 -0800, Kim Cascone wrote:
... and the devs seem highly resistant to the idea of writing in full jack
support - they've certainly been asked often enough. Maybe it's due to
cross-platform implications.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
when I connect the output of Audacity to
Timemachine _by hand_ using
Patchage
there is a delay in the stereo sound file between the start of audio in
ch1 & 2
which is equal to the time at which the connections are physically made
to timemachine
in other words:
- I create a 10 sec file of 440Hz sine in Audacity
- play it back on loop
- go to Patchage and connect ch1 from PortAudio (which is actually
Audacity) to Timemachine wait 10 seconds then connect ch2 to the other
input of Timemachine
- hit record on Timemachine wait a couple of seconds
- stop record on Timemachine
- stop playback of 440 sine in Audacity
- open the sound file recorded by Timemachine in Audacity
- look at the start of the sound file
- there is a delay between channels seen in the sound file equal to the
time I waited to connect ch1 & ch2
Maybe you could try with a JACK-native audio player. See below...
side question: why do the outputs of Audacity
appear as PortAudio in Jack?
is it a reference to virtual ports being instantiated when playback
occurs in Audacity?
No, it's because Audacity does not support JACK. It only half-manages it
through using the PortAudio library.
Peter. 
11:49 a.m.
Excerpts from Folderol's message of 2011-01-22 11:38:37 +0100:
On Sat, 22 Jan 2011 08:37:04 +0000
Peter Nelson <peter(a)fuzzle.org> wrote:
Jack is available on Linux, Windows, OSX and Solaris as far as I know,
that' pretty cross platform if you ask me.
Anyway, I don't know whether this is a timemachine or audacity error.
The error probably won't occur with an audio editor that doesn't require
you to connect during playback.
On Fri, 2011-01-21 at 18:25 -0800, Kim Cascone
wrote:
... and the devs seem highly resistant to the idea of writing in full jack
support - they've certainly been asked often enough. Maybe it's due to
cross-platform implications. when I connect the output of Audacity to
Timemachine _by hand_ using
Patchage
there is a delay in the stereo sound file between the start of audio in
ch1 & 2
which is equal to the time at which the connections are physically made
to timemachine
in other words:
- I create a 10 sec file of 440Hz sine in Audacity
- play it back on loop
- go to Patchage and connect ch1 from PortAudio (which is actually
Audacity) to Timemachine wait 10 seconds then connect ch2 to the other
input of Timemachine
- hit record on Timemachine wait a couple of seconds
- stop record on Timemachine
- stop playback of 440 sine in Audacity
- open the sound file recorded by Timemachine in Audacity
- look at the start of the sound file
- there is a delay between channels seen in the sound file equal to the
time I waited to connect ch1 & ch2
Maybe you could try with a JACK-native audio player. See below...
side question: why do the outputs of Audacity
appear as PortAudio in Jack?
is it a reference to virtual ports being instantiated when playback
occurs in Audacity?
No, it's because Audacity does not support JACK. It only half-manages it
through using the PortAudio library.
Peter. 
11:57 a.m.
On Sat, Jan 22, 2011 at 11:49:38AM +0100, Philipp Überbacher wrote:
Anyway, I don't know whether this is a timemachine
or audacity error.
The error probably won't occur with an audio editor that doesn't require
you to connect during playback.
I just did a short test with timemachine and a signal from a soundcard:
* connect first input
* wait a few secs
* connect second input
* start timemachine recording for a few seconds
Of course in the recorded file the second channel starts later,
this is because timemachine has recorded ten seconds or so before
I actually started it and this includes the time the connections
were made. But the two signals are absoulute in sync, no problem.
I wonder how the OP notices that one channel is delayed by some
time - you can' see this with a sine wave...
Ciao,
--
FA
There are three of them, and Alleline.
11:58 a.m.
On Sat, Jan 22, 2011 at 3:25 AM, Kim Cascone wrote:
when I connect the output of Audacity to Timemachine
_by hand_ using
Patchage
there is a delay in the stereo sound file between the start of audio in ch1
& 2
which is equal to the time at which the connections are physically made to
timemachine
in other words:
- I create a 10 sec file of 440Hz sine in Audacity
- play it back on loop
- go to Patchage and connect ch1 from PortAudio (which is actually Audacity)
to Timemachine wait 10 seconds then connect ch2 to the other input of
Timemachine
wait for ten seconds here, and see if it still happens (see below).
- hit record on Timemachine wait a couple of seconds
- stop record on Timemachine
- stop playback of 440 sine in Audacity
- open the sound file recorded by Timemachine in Audacity
- look at the start of the sound file
- there is a delay between channels seen in the sound file equal to the time
I waited to connect ch1 & ch2
Could this be due to the 'timemashine'-feature of timemashine? When
started up, it buffers (default) ten seconds of what arrives at its
input, as soon as the record button is hit it adds the ten seconds to
the recording. I'm just wondering whether timemashine just records you
manually doing the connections.
just to be sure.
best,
d
5058
days inactive
5058
days old
linux-audio-user@lists.linuxaudio.org
5 comments
6 participants
participants (6)
-
David Adler -
Folderol -
fons＠kokkinizita.net -
Kim Cascone -
Peter Nelson -
Philipp Überbacher