LIVEWIRE-WAN LINK |
11
MPEG Transmit
Set the codec type, bitrate, and stereo/mono mode you want to use for this channel.
Use the Encoder Type dropdown to select the method of MPEG encoding you wish to use.
Along with serveral options for AAC, MP3 and MP2 encoding, you can also choose linear
(uncompressed) audio and GPIO only.
The
Protocol type
is either UDP or TCP. There are tradeoffs in this choice that are only
fully understood if you have knowledge of this aspect of IP networks. Here is a simple
overview: UDP is the usual choice because it offers lower delay than TCP and is not
impaired by TCP’s flow/rate control. However, with UDP, there is no network recovery of
lost packets as there is with TCP, so the codec’s concealment is used to reduce the audibility
of these events.
With AAC, up to around 10% random packet loss can be effectively concealed. This is
one of the strengths of AAC. The other codecs also have concealment, but it will not be as
effective.
Network links with high and guaranteed Quality of Service will almost always let you use
UDP without trouble.
The Output Configuration section allows you to specify the IP of the main output, as well
as up to 3 more replicated streams.
The
Enable SHOUTcast protocol
option is used only for streaming with an external
server, so is not checked.
V-Mixer and V-Mode
Virtual Mixer (or VMIX) is a “virtual mixer” with 40 stereo input channels, a direct output
for each channel, 8 submixer outputs, and one master out. The 40 channels are divided
equally among the 8 subgroups providing 5 stereo channels in each subgroup mixer. Using
these, you can combine multiple Livewire audio channels into a single, summed channel,
which can then be sent to a receiving iPort.
VMODE is an adjunct to the Virtual Mixer; its job is to help strip, sum, or compile a
custom audio stream from other avail able streams in the network. Using VMODE, you can
