Archiv der Kategorie: Codec 2

Open source Sprachcodec der ohne patentiertem Chipdesign möglich ist, für den Funkamateur das richtige ?

FreeDV kubuntu 13.10

aktuelle news quelle: Forum digitalvoice :

jim ki6njf wrote :

I have freedv running on both ubuntu 13.10 and debian jessie now.  In both cases I had to edit pulseaudio’s config file, /etc/pulse/daemon.conf  and remove the comment semicolon in front of the lines:

 high-priority = yes
 nice-level = -11
to eliminate the stuttering in freedv’s audio.
Reboot after you change it.

To test it, use „ps“ to get the process ID of pulseaudio. Run this:

    renice -11 process-id

It should print this:

    old priority -11, new priority -11

If it prints that the old priority is 0, it did not get set as you wish.

Also experiment with these configuration fields:

; lock-memory = no
; cpu-limit = no

; realtime-scheduling = yes
; realtime-priority = 5

Locking the memory would keep pulseaudio from being swapped out on a low-memory system, and swapping would make it stutter. The realtime scheduling and priority are real-time versions of what you’ve just adjusted, I have not looked into what the proper values would be. cpu-limit may pin the daemon to a specific processor and maybe reduce process switch overhead. But I haven’t investigated.

If you have an old kernel, try a newer one. There has been recent work on real-time scheduling.

We are really asking here for a hard real-time priority. It may be that your system doesn’t have the memory to offer that (the real-time process should not swap) and it may also be that Linux isn’t quite a real-time OS, although this is certainly improving.


Codec2 Infos in loser Reihenfolge

An nachfolgender Stelle ist in englischer Sprache die Konfiguration für ein RaspberryPI  Codec2 GMSK Modem mit USB Soundkarte zum Anschluss an 9k6 Tranceiver beschrieben.

Codec2 GMSK Modem Link

Aufgrund der erforderlichen höheren Rechenleistung vor allem aber intensivem USB Schnittstellenverkehr ist der RaspberryPI weniger geeignet, weil dieser einen Fehler in der vom Prozessor kommenden USB Schnittstelle hat, bald werden bestimmt auch die neueren Boards darauf angepasst werden, dann sollte es noch besser funktionieren …

vy73 Stefan dk6px