A network broadcaster may own multiple stations in different regions. The broadcast content is generated in central master control room and delivered to remote staions for transmission. Some of the remote stations may not be manned at all. The operators need to have a way to monitor the quality of video services in remote stations from the central location.
Here we will describe a solution for monitoring TV signal quality in remote stations. This solution works even when there is no high bandwidth connection to the remote stations.
Figure 1: Architecture Diagram of Mividi Remote Monitoring
Monitoring Architecture
Figure 1 shows the architecture of Mividi remote monitoring solution. In each remote station, the local RF signal is received and converted to an IP stream using an RF receiver/converter. The IP stream will be fed to the Mividi TSM probe for monitoring and analysis. The Mividi TSM probe is a combination of multiviewer and transport stream analyzer. It will decode video and audio, check video frame errors such as black and frozen frames, and measure the audio loudness levels. The TSM probe will also perform comprehensive transport stream analysis, and monitor TR 101 290 transport stream errors in all priority levels.
To view the video programs and test results on the TSM probes in the remote stations, a Mividi IP multiviewer (IMS120) and a TSM Web server are installed in a central monitoring station, such as a master control room (MCR) or network operation center (NOC). The TSM probe can capture its own multiviewer display screen and generate a transport stream of multiviewer screen capture to be sent back to the central monitoring station for remote view under certain network setup. The IP multiviewer system will collect and display multiviewer streams from each remote site. Using the same system, it can also monitor local TV signals in the MCR or NOC if required.
In certain cases, if the TSM probes are sitting behind routers and are not visible from the central monitoring station, the TSM probe can push the test data to a TSM web server installed in the central station. Users can use a normal web browser to access the TSM web server and view test results from different sites.
The Mividi software runs on a Windows computer, so many remote access tools for Windows may be used to manage the probe as well. For broadcast stations with limited number of channels, a small computer, such as Intel NUC, is sufficient to run the software application. A more powerful server may be used for broadband sites with many channels to monitor.
Key Features of Monitoring Probe
The remote TSM probe consists of three key modules, including IP multiviewer, TS analyzer, and a basic stream recorder. The main features of the TSM probe include:
- Multiviewer Monitoring: Supports MPEG-2, H.264, H.265, VC-1, and most common audio encoding formats including MP3, AAC, AAC+, Dolby AC3. Display subtitle or closed captioning.
- Comprehensive TS Analysis: Provides comprehensive TS analysis for both DVB and ATSC streams and monitors TS error checks based on DVB test guideline TR 101 290 and reports all three priority level errors.
- Calculates audio loudness level and displays LKFS values.
- Error Logs and Alarms: Provides multiple ways of sending error alarms, including email, visual displays on a multiviewer screen, and audio sound. The alarms can be triggered by errors selected by users, such as loss of input, audio or video components, black or frozen frames, etc.
- Captures multiviewer display and generates a video transport stream for remote view.
Central Monitoring System
The central monitoring system in the MCR or NOC consists of a multiviewer system, such as Mividi IMS120 or WSM120. The multiviewer streams sent by the TSM probes in remote stations can be displayed in the central station multiviewer. Therefore, individual PIP (Picture in Picture) displays a video which is a multiviewer screen display of a probe. Multiple multiviews from different stations can be displayed on a single monitor screen.
The central multiviewer system can also be used to monitor local TV signals in the MCR or NOC. The normal TV program can be displayed along with the return multiviewer streams from remote stations. The effect of hybrid display of both normal programs and remote multiviewers is shown in the following figure.
Figure 2: Multiviewer Display in Central MCR or NOC
The central monitoring system may also consist of the TSM Web server (TSM Web). The TSM Web is especially useful in the case the TSM probes are not directly accessible from the central monitoring station. In this case, the test data in the TSM probes must be pushed to the TSM Web. These test results to be pushed to the TSM Web in the central station include:
- Video program thumbnails.
- Transport stream information such as programs, PIDs, PID and stream bitrate, ect.
- Transport streams errors including TR 101 290 priority 1, 2, and 3 errors.
- All decoded table data including ATSC PSIP and DVB SI tables.
- Save error Logs and alarms logs.
The TSM Web is a normal web server so users can access the TSM Web and view test results from different remote probes using an Internet browser. Figure 3 is an illustration of the web interface UI.
Figure 3: TSM Web User Interface
Setup Under Different Network Environment
1. Probes Are Accessible Using VPN
If probes are accessible using VPN by the central monitoring system, the probe data can be obtained by the central monitoring system using pull mode. The central monitoring system can get the multiviewer stream from probes using the UDP, RTP or HTTP format. If the connection bandwidth between a probe and the central monitoring station is good, UDP or RTP streams are preferable because they cause less delay. If the connection is slow, HTTP streaming is recommended since it is more resilient to handle network issues caused by the bad Internet connection.
To collect test data from each probe, the TSM Web server can access to each probe by pull data from probes. The pulling mode is more flexible such that an entire video stream may be downloaded and played by a remote user. The TSM Web server can be used as a focal access point for remote access from outside of VPN.
2. Probes Not Visible from Central Station
If probes are behind routers that are not open for Internet access, the data from each probe must be sent to the central TSM Web server using push mode. In this case, the central TSM Web is not be able to reach the probe using an external IP address. The data communication must be initiated by the probe. Figure 4 shows data flow under this setup. Once a communication channel is established between the probe and the TSM Web server, the TSM Web can send command to the probe and will receive test data from the probe. For example, each probe can send video thumbnails in every 1-2 second interval to show that video programs are alive and can be correctly decoded.
Figure 4: TSM Web / Probe Communication Flow
Summary
We provide a solution for broadcasters who own multiple stations to monitor video service quality in remote sites from the central monitoring station, such as MCR or NOC. The solution uses a combination of the Mividi TSM Probes in remote site and the Mividi Multiviewer and TSM Web server in the central monitoring station. The solution can work for different network environment whether the remote sites are within the same VPN as the central monitoring station or without external IP to access the probes.