Re: [ecasound] schedule effects

On Sat, Jun 06, 2009 at 01:13:00AM +0200, laurent schwartz wrote:
> Hy julien,
>
> my kernel version is 2.6.24-24-rt #1 SMP PREEMPT RT Wed Apr 15 18:09:25 UTC
> 2009 i686 GNU/Linux.
>
> laurent@email-addr-hidden-inspiron1525:~$ jackd --version
> jackd version 0.109.2 tmpdir /dev/shm protocol 22
>
> It would be great to have a configuration wizard for jackd searching and
> finding the best available configuration for the hardware.
> A tool that can check your setup for every piece of configuration needed for
> jackd.

I would like to see a tool that would set up Linux audio
entirely. A wizard for setting up JACK would be a great
start.
 
> Indeed, i'm not new to linux. But i learn every day about linux and software
> packages available ! I've already tried to use ardour with jack audio apps
> but i abandonned because of xruns problems. I get cracky records ...
>
> I decided to find a lighter solution that feet my needs such as ecasound
> (for audio recording), midish (MIDI sequencer/filter) and timidity (MIDI to
> WAV) that are command line tool (can be used for batch processing and live
> session).

Ecasound is definitely one of the lightest tools available,
and has an advantage that it can do a lot without requiring
JACK.
 
> What i would like to do is to transform a MIDI file to a wav file (using
> timidity batch mode). Once i get the playback track, i need the transport
> information (time mn/sec/msec measure and beat information) when playing in
> order to know when to apply effects with ecasound on the recorded microphone
> track.

One approach I've been using with Nama is setting marks. I can
see the exact time for the marks I set, and some commands
will take the mark label as an argument.

In future I anticipate being able to capture midi control
signals for altering effects and then to be able to play
them back.

I would also like to be able to do what you seem to want,
applying effects at specific times. One of the issues with
that is latency. Applying effects in realtime in Ecasound
causes a pop due to the latency the effect adds to a signal
chain.

> Once i built the ecasound effect-preset for the microphone track, i record
> the session using ecasound and can hear the effects on microphone track
> while performing.
>
> I know that to do this, i need jackd otherwise, using alsa device, it will
> surely introduce to much latency. If using alsa device, effects should be
> calculated in batch mode.

I think that is worth testing. You can set the buffer size
with Ecasound, and if it is sufficiently small, you won't
get much latency. The effects that bring additional latency
do so regardless of using Ecasound, JACK, ALSA, etc.

Some latency in inherent in all USB audio devices.
 
> I need to resolve the xruns problem in order to use jack.
>
> Three options have been mentioned to optimize my setup:
> - build a custom kernel (do i have hardware that require a tuned RT kernel
> ?)
> - change interrupt priorities
> - change the windowing system (for instance gnome) to a lighter one (fvwm,
> ... ?)
>
> I don't know how to set priority in interrupts (is this possible ?)
> (graphic i915 cards, audio Intel card and USB audio card).
> /proc/interrupts
> CPU0
> 0: 522 IO-APIC-edge timer
> 1: 4753 IO-APIC-edge i8042
> 8: 7 IO-APIC-edge rtc
> 9: 0 IO-APIC-fasteoi acpi
> 12: 1056 IO-APIC-edge i8042
> 14: 96997 IO-APIC-edge libata
> 15: 0 IO-APIC-edge libata
> 16: 3 IO-APIC-fasteoi ohci1394, i915@email-addr-hidden:0000:00:02.0
> 18: 356346 IO-APIC-fasteoi uhci_hcd:usb1, uhci_hcd:usb4,
> ehci_hcd:usb7
> 19: 7390 IO-APIC-fasteoi uhci_hcd:usb2, uhci_hcd:usb5, HDA Intel
> 20: 29 IO-APIC-fasteoi ehci_hcd:usb3, uhci_hcd:usb6
> 21: 12 IO-APIC-fasteoi sdhci:slot0
> 218: 7 PCI-MSI-edge iwl3945
> 219: 60407 PCI-MSI-edge eth0
> 220: 59687 PCI-MSI-edge ahci
> NMI: 0 Non-maskable interrupts
> LOC: 14279337 Local timer interrupts
> RES: 0 Rescheduling interrupts
> CAL: 0 function call interrupts
> TLB: 0 TLB shootdowns
> TRM: 0 Thermal event interrupts
> SPU: 0 Spurious interrupts
> ERR: 0
> MIS: 0
>
> Kindest regards,
> Laurent

-- 
Joel Roth
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