19 Apr
2010
19 Apr
'10
9:37 a.m.
Hello,
i want to grab some external sources (cdplayer) with jack. i run a jack
instance with 48000 Hz and it works perfectly with my cd player and ardour.
but if i take a cheaper cdplayer, the signal will only be came in with 44100,
because there seems no resample and sync between the master (soundcard) and
slave (cheapoCD) . so, the signal will always being played to slow. i found a
workaround with a small external box, which resamples the incoming signal
before it get into the soundcard.
Since a while, i think about a software solution, which puzzles me a bit. if i
doing the process without the external resampler, what must be done with the
signal.
If the original source is 44100 Hz, the incoming signal is 48000 (because of
jack). if i try to resample it, the current buffer get shorter, because the
signal need to be decreased.
How can a correct resampling process be done?
Thanks c~
19 Apr
19 Apr
10:37 a.m.
On Mon, Apr 19, 2010 at 12:38:35PM +0200, Conrad Berhörster wrote:
i want to grab some external sources (cdplayer) with
jack. i run a jack
instance with 48000 Hz and it works perfectly with my cd player and ardour.
but if i take a cheaper cdplayer, the signal will only be came in with 44100,
because there seems no resample and sync between the master (soundcard) and
slave (cheapoCD) . so, the signal will always being played to slow. i found a
workaround with a small external box, which resamples the incoming signal
before it get into the soundcard.
Since a while, i think about a software solution, which puzzles me a bit. if i
doing the process without the external resampler, what must be done with the
signal.
If the original source is 44100 Hz, the incoming signal is 48000 (because of
jack). if i try to resample it, the current buffer get shorter, because the
signal need to be decreased.
How can a correct resampling process be done?
Jack clients all see the same sample rate and buffer
size, so the resampling would need to be done in the
backend (the 'driver' that links Jack to ALSA or FFADO).
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
11:57 a.m.
Hello Fons,
thank you for your answer
Am Montag 19 April 2010 14:32:45 schrieb fons(a)kokkinizita.net:
Jack clients all see the same sample rate and buffer
size, so the resampling would need to be done in the
backend (the 'driver' that links Jack to ALSA or FFADO).
Since i'm using ALSA, i can use the dmix plugin.
thanks c~
1:10 p.m.
On Mon, Apr 19, 2010 at 12:38:35PM +0200, Conrad Berh?rster wrote:
Hello,
i want to grab some external sources (cdplayer) with jack. i run a jack
instance with 48000 Hz and it works perfectly with my cd player and ardour.
but if i take a cheaper cdplayer, the signal will only be came in with
44100, because there seems no resample and sync between the master
(soundcard) and slave (cheapoCD) . so, the signal will always being
played to slow. i found a workaround with a small external box, which
resamples the incoming signal before it get into the soundcard.
Your spdif sound card might have a sample rate converter. If it did,
most likely the work flow would be to set jack at 48k and then just play
normally and the sound card would convert from the incoming 44.1k to the
48k it is set to. The SRC chip in your sound card (again, presuming it
has one, which I think is likely) is probably similar to whatever is in
the external box you've tried.
Since a while, i think about a software solution,
which puzzles me a
bit. if i doing the process without the external resampler, what
must be done with the signal.
If the original source is 44100 Hz, the incoming signal is 48000 (because of
jack). if i try to resample it, the current buffer get shorter, because the
signal need to be decreased.
How can a correct resampling process be done?
Unless there is a real need to do this in realtime, say for a live
performance, I would suggest just ripping the CD and using a software
sample rate converter on the resulting files. I'd be surprised if this
couldn't be done in better than realtime on todays systems, meaning you
might be able to rip and convert a 60 minute CD in under 30 minutes.
3:11 p.m.
Hello Joshua,
Am Montag 19 April 2010 17:07:35 schrieb Joshua Boyd:
On Mon, Apr 19, 2010 at 12:38:35PM +0200, Conrad
Berh?rster wrote:
i own a gina 3G. i don't think, it has such a chip. anyway, never had heard,
how to obtain an extra SRC Chip on any soundcard. has ALSA/Jack the
possibilty to do such a thing?
As i have read today, Spdif seems close to AES/EBU, which doesn't sent sample
rate information. so, there seems to be different implementations in different
Players. Some are better, some not. So, i have no chance to check that in any
way except hearing. hmm.
Hello,
i want to grab some external sources (cdplayer) with jack. i run a jack
instance with 48000 Hz and it works perfectly with my cd player and
ardour. but if i take a cheaper cdplayer, the signal will only be came in
with 44100, because there seems no resample and sync between the master
(soundcard) and slave (cheapoCD) . so, the signal will always being
played to slow. i found a workaround with a small external box, which
resamples the incoming signal before it get into the soundcard.
Your spdif sound card might have a sample rate converter. If it did,
most likely the work flow would be to set jack at 48k and then just play
normally and the sound card would convert from the incoming 44.1k to the
48k it is set to. The SRC chip in your sound card (again, presuming it
has one, which I think is likely) is probably similar to whatever is in
the external box you've tried.
Unless there is a real need to do this in realtime, say for a live
performance,
What a pity, i need it in realtime. ;=(
i have written a software, which mixes some files. and now i want to add the
possibility to add external sources like a CD Player.
but thanks for your thoughts
sizu c~
5365
days inactive
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linux-audio-dev@lists.linuxaudio.org
4 comments
3 participants
participants (3)
-
Conrad Berhörster -
fons＠kokkinizita.net -
Joshua Boyd