[asterisk-users] TC400B and show transcoder

[Ben Dinnerville]

Hi All,

I have recently installed a TC400B card into a system and am trying to 
get it to work. As far as I ca tell from the docco on Digiums website, 
there is no config as such unless you want to enable  / disable only 1 
codec, otherwise by default it runs as 92 channels of either.

I have tried asterisk 1.4.9, 1.4.10 and 1.4.10.1 along with zaptel 1.4.4 
and addons 1.4.2. The zaptel modules all apear to be loaded correctly 
(loading wctc4xxp loads up zttranscode and zaptel). Dmesg shows that the 
card has been found:

Registered codec translator 'DTE Encoder' with 92 transcoders 
(srcs=0000000c, dsts=00000101)
Registered codec translator 'DTE Decoder' with 92 transcoders 
(srcs=00000101, dsts=0000000c)
Zaptel DTE (g.729a / g.723.1 5.3kbps) Transcoder support LOADED (firm 
ver = 56)
Found and successfully installed a Wildcard TC: Wildcard TC400P+TC400M


and the card has its own interrupt -
193:    1871532    1896779   IO-APIC-level  tc400b

But when ever we need to do a transcode, ie playing back a wav file on a 
g729 channel, the audio is complete rubbish, with a lot of stutters in 
it (sounds like a recording does when you upload a file in the wrong 
sample rate etc) - the file that we are playing back is a wav file that 
has existed on the system and has been successfully played back with the 
soft g729 transcoding and also plays back fine when the channel is alaw, 
just not when the channel is g729. The same issue occurs when a 
transcode has to happen from a handset to a IP trunk, eg alaw on the 
handset and g729 on the trunk channel, the audio stream is non 
comprehensible.

The other issue is that whilst all the modules apear to be loaded 
ocrrectly, and a show translation shows that the codes are supported 
without the presence of a g729 key:

pbxla*CLI> core show translation
          Translation times between formats (in milliseconds) for one 
second of data
           Source Format (Rows) Destination Format (Columns)

           g723 gsm ulaw alaw g726aal2 adpcm slin lpc10 g729 speex ilbc 
g726 g722
      g723    -   3    1    1        3     3    2     3    2     -   12 
    3    -
       gsm    3   -    2    2        2     2    1     2    3     -   11 
    2    -
      ulaw    1   2    -    1        2     2    1     2    1     -   11 
    2    -
      alaw    1   2    1    -        2     2    1     2    1     -   11 
    2    -
  g726aal2    3   2    2    2        -     2    1     2    3     -   11 
    1    -
     adpcm    3   2    2    2        2     -    1     2    3     -   11 
    2    -
      slin    2   1    1    1        1     1    -     1    2     -   10 
    1    -
     lpc10    3   2    2    2        2     2    1     -    3     -   11 
    2    -
      g729    2   3    1    1        3     3    2     3    -     -   12 
    3    -
     speex    -   -    -    -        -     -    -     -    -     -    - 
    -    -
      ilbc    4   3    3    3        3     3    2     3    4     -    - 
    3    -
      g726    3   2    2    2        1     2    1     2    3     -   11 
    -    -
      g722    -   -    -    -        -     -    -     -    -     -    - 
    -    -

The show transcoder command listed in the documentation does not exist. 
There is no "show transcoder" or "core show transcoder" command 
available on the system. I have checked the menu options for the build 
and cannot see any specific item that needs to be enabled for this 
command to be available but have a feeling that the lack of this command 
and the horrible transcoded audio quality are related. Or is it just 
that the show transcoder command is only available in 1.2 and not in 1.4?


Another quick (hopefully) question - does the TC400 card provide a 
zaptel timing source, or do you still need to load ztdummy in the case 
of not having another card in the system?


Any info or experiences would be great.

Thanks in advance.

Ben