Difference between revisions of "Which codecs should I choose for devices"

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Make sure same codec is chosen between devices you are trying to communicate.
Make sure same codec is chosen between devices you are trying to communicate.
=Fax=
If your system/provider/devices does not support T38 you should use G711 codec for fax transmitting/receiving.


=Notes=
=Notes=


Make sure you have always selected audio codec! Otherwise you will not be able to place calls!
Make sure you have always selected audio codec! Otherwise you will not be able to place calls!

Revision as of 09:19, 30 April 2008

It depends.

What codecs are supported?

Audio:

  • G.711 A-law
  • G.711 u-law
  • G.723.1
  • G.726
  • G.729
  • GSM
  • iLBC
  • LPC10
  • Speex
  • ADPCM
  • 16 bit Signed Linear PCM

Video:

  • H.261
  • H.263
  • H.263+
  • H.264

Audio codecs

Most commonly used are:

  • G711
  • G729

G711

PSTN quality codec which is supported in 99% of all devices/providers (but often disabled to save traffic).

It has best quality but highest bandwidth (64kbps + ~20 kbps overhead ~= 84kbps to one direction).

It comes in 2 flavours - G711u (ulaw) - used in USA, and G711a (alaw) - used mostly in Europe and other countries.

G729

Little worse quality but is often used because it saves traffic (~8kbps + ~20kbps overhead ~= 28kbps to one direction).

It needs to be installed separately and it is not free.

Video

Read manual for your device to check which codec is supported on your device.

H263/H264 are most popular.

Make sure same codec is chosen between devices you are trying to communicate.

Fax

If your system/provider/devices does not support T38 you should use G711 codec for fax transmitting/receiving.

Notes

Make sure you have always selected audio codec! Otherwise you will not be able to place calls!