Specifications

62 Implementation of a Low Cost Video Wall using Raspberry Pi devices
CHAPTER 5. SYNCHRONIZATION
In a Video Wall the idea of synchronizing a set of screens is that you can use individual
content on each screen but still get the monitors to work together in a synchronized
way. In the figure below there are three animations (video clips) that are synchronized
to start simultaneously and maintain this synchronization during all the streaming.
Figure 29: Video Wall syncronization example
The purpose of this chapter is to verify the synchronization between the two Raspberry
Pi devices that are used during the project. To do so, Wireshark, a network analyzer
tool, will be used to explain the basis of the packets captured. The synchronization
evidences shown in this chapter are achieved with GStreamer and FFmpeg
frameworks.
5.1. GStreamer
In this case synchonization
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in the Video Wall will be demonstrated by using
GStreamer.
First of all, the GStreamer pipeline statistics indicate that there is just one clock
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handling the 2 video flows and another clock that handles the local audio.
Figure 30. GStreamer System clock and audio clock
Second of all, when observing the Wireshark capture below, the Synchronization
Source parameter (SSRC) is the same for both flows.