User`s manual

LOLA: Low Latency Audio Visual Streaming System
1. Introduction
Lola is an Audio Visual Streaming System developed by “Conservatorio di Musica G.
Tartini”, Trieste, Italy, in collaboration with GARR, the Italian Academic and Research Network.
LOLA goal is to provide a tool for real-time audio/video “natural” distance human interaction. It
was originally conceived for distance music performances, education and production, but can be
used for any other scenario where real-time interaction is required. A special attention has been
paid to the optimization of the signal processing and transmission in order to keep the system
latency as low as possible, below the human delay perception threshold.
The system is based on high performance audio/video acquisition hardware, and on the
integration and optimization of audio/video stream acquisition, presentation and transmission. The
LOLA system also requires very high performance Wide Area and Local Area Networks: 1 Gigabit
per second end-to-end connection is the minimum suggested configuration.
2. Hardware and Operating System
requirements
In order to achieve a low transmission and presentation latency, LOLA relies on software
optimization and on high performance audio and video devices. Low latency video in particular has
been achieved by adopting a family of industrial video grabbers which at the moment are only
supported under the MS Windows Operating System. To date, LOLA has been tested on both MS
Windows XP and MS Windows 7 (32 bits and 64 bits versions). As Windows XP is being phased
out, and Windows 7 offer better perfomances for LOLA, we suggest to use Windows 7 as the base
operating system. Furthermore, future LOLA releases (v1.4.0) will no more support Windows XP.
2.1. Audio input/output hardware requirements
Low latency audio performance requires that small in/out audio buffers can be used, that no
bottlenecks are present in the data transfer between the converters and the system, and that robust
and efficient software drivers are available for the OS in use. USB and FireWire (IEEE 1394)
external devices do not offer such a fast data acquisition processing, thus LOLA uses a PCI/PCIe
internal device and a reliable ASIO driver. To date, the following Audio boards have been tested and
have shown very good performances:
– RME HDSPe-AIO (PCI-Express internal card)
– RME Hammerfall HDSP 9632 (PCI internal card)
– RME Multiface II (PCI/PCIe host card + external ADC/DAC box)
2.2. Video input hardware requirements
Fast video acquisition and streaming relies on a family of video grabbers by BitFlow Inc.,
which provides high hardware performances and a versatile programming API for low-level video
processing control. The BitFlow video grabbers currently used by LOLA are the analog ones, like