tree 123e70863cd9e265c1a230de437d2971ae53f77c
parent 91eeeae312b3dfc54fc577b437c481811ff60d4a
author Holger Hans Peter Freyther <holger@moiji-mobile.com> 1403890058 +0200
committer Holger Hans Peter Freyther <holger@moiji-mobile.com> 1406032973 +0200

mgcp: Document transcoding semantic and follow it

Transcoding from GSM to PCMA can lead to the MGCP MGW sending
two PCMA packages with the same sequence number and timestamp.
Once with the encoded audio and once completely empty.

This is because "state->dst_packet_duration" is 0 in most cases
(unless a ptime is forced) and we attempt to encode audio even
if there are not enough samples. The encode_audio return will
return 0 in that case which is not trated as an error by the
mgcp network code.

Handle rc == 0 specially and document the semantic.