User`s manual

LOLA: Low Latency Audio Visual Streaming System
4.1. Local audio and video settings
Before attempting to connect to a remote host, the user should correctly configure the local
audio and video options. The Lola Setup dialog (in the Options Menu, Fig. 3) allows to select the
desired ASIO audio device, the video camera file, the desired video frame rate (30 up to 60 fps, but
30 or 60 are the standard suggested values), the video compression (default NONE) and the
network interface controller.
If audio multichannel is enabled (by your activation code), it also allows to set the number
of used audio channels. From this menu it is also possible to specify from which audio input
channel from the RME audio card you shall collect the local audio input. You can control from
which audio input channel LOLA shall receive input by using the “Audio Input Offset” setting. If
set to 0 (default value), LOLA will receive audio starting from the first RME channel, which
usually is an analogue input one.
As an example, imagine you have multichannel audio enabled and your audio card has the
following list of input audio channels:
AN1 AN2 SP.L SP.R A1 A2 A3 A4 A5 A6 A7 A8
and you want LOLA to receive audio input from the 8 ADAT (A1...A8) channels. Then you need to
set “AudioInputOffset” = 4, thus LOLA will skip the first 4 channels, and “N. Audio Channels” = 8
in the Lola Setup dialog box. If you request more audio channels than available, LOLA will signal
an error. An easy way to detect your RME audio card configuration is to see the HDSP Matrix from
the card internal mixer (see appendix E). The “input channels” are listed as the top row in the
matrix.
It is recommended to verify that audio input is working properly and the input latency is low
as expected. A rough test can be done by switching on input-to-output redirection (using the “Local
audio On/Off” flag available on the control panel in the main window, see Fig. 4) and using
headphones connected to the LOLA audio card output to avoid an audio feedback effect. Further
checks on the audio setup can be done using the appropriate audio card mixer/setup application (see
for example Appendix E).
LOLA can also pre-amplify audio input by 6dB in case this is needed; just set “TX audio
level” to “2.0” if you want this pre-amplification to happen.
If the local video camera is connected and the correct camera file is selected, you should
also see in the “Local Host” windows your local video. Also in this case you should check that the
local video latency is low as expected. You should also check that the local audio and the local
video are synchronized correctly.
The features of the local video stream (resolution / pixel depth / frame rate) are shown on
top of the video frame, as shown in Fig. 5 (“Local host: 640x480, 8 bit, 50 FpS” for example).
It is finally possible to enlarge the video frame by selecting the desired zoom ratio form the
menu available on the video frame (Fig. 5) or simply by resizing the window with the mouse (the