Vidicode V-Tap VoIP Manual page 25

SD Auto Close Packet Count
SD Auto Close Timeout in secs
These two parameters are used by the system to close files on SD
card automatically. As soon as you insert an SD card, a file is opened
for writing and recorded data is put into it. Packets are counted each
second again and when the installed threshold is reached, the
timeout becomes active. When the Packet Count is under the
threshold for time of the installed timeout, the current open file is
closed. A new file is opened immediately after that.
One normal VoIP call produces about 100 packets per second for the
duration of the call. After the call, a few or no packets are received.
In this way, the Auto Close function can be seen as an off/on-hook
detector. The files on SD card will then contain complete calls. Of
course, this is only true when one VoIP phone is connected. With
more phones connected and more calls active at the same time, the
files can also contain multiple calls.
SD Max Files on Card
The maximum number of files on the card has 2 purposes.
First of all, it makes the directory on the card more manageable by
the system and any PC. Too many files in one directory make a slow
system. The default number of 5000 is reasonable.
Secondly, a system can be built to use the card as an endless buffer,
without the problem that the card is getting full. However, this must
be calculated carefully and depends on the size of the card, the
maximum file size (see below), the auto close function (see above)
and the amount of recorded data (number of connected phones).
After the maximum number of files has been reached, the file write-
counter is reset and older files are overwritten automatically.
SD Max File Size in MB
When a file on SD card reaches the maximum file size, the file is
closed for further writing and then send to the Tunnel server, if that
function is enabled. The name counter is incremented at the same
time and a new file is opened.
An uncompressed VoIP call produces roughly 24 Kbytes per second.
This means a little less than 90 Mbytes per hour. The default of 250
Mbytes is therefore enough for about 3 hours of recording. A call
that takes longer will continue in the next file, without loss of data.
V-Tap VoIP Manual EN v2.7 Oct 2018 © 2017-2018 Vidicode 25