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OVERLAND PARK MAIN CAMPUS - In streaming live to its four campuses, Legacy Christian Church tries to closely replicate the experience at the transmitting location, so they also transmit the side-screen images, which are close-up shots (IMAG) with graphics.
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BLUE VALLEY SATELLITE CAMPUS - A local worship team handles worship music at each campus, but sometimes a special song is done at the transmitting site and the remote campuses experience that through their video feeds.
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LEE’S SUMMIT SATELLITE CAMPUS - "...when we realized that the second stream was a close-up of the first, and lip-sync level synchronization was needed, that was when we had an issue.” David Buck, Harris Broadcast
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“Our main campus—the transmitting site—has a 40 Mbps fiber connection to the Internet, with each satellite campus having a 20 Mbps connection.” SHANE RUSHIK, EXECUTIVE DIRECTOR OF TECHNOLOGY, LEGACY CHRISTIAN CHURCH, OVERLAND PARK, KS
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OLATHE SATELLITE CAMPUS - This adds another level of complexity to the streaming process since the IMAG stream needs to be perfectly synced to the main video to avoid distracting visual delay.
The concept of satellite campuses in the church has been around for well over a decade, and there are a variety of approaches that churches can take with the concept. Some may choose to have each campus be independent Sunday mornings—their own teaching pastor, their own worship team, etc. Others have local music teams, but each campus presents the same message from the same teaching pastor. In the latter case, the teaching pastor is “live” at one campus, and the satellite campuses utilize video to present the pastor's sermon to the congregation.
Within this format, the delivery of that video to the satellite campuses also takes on several forms. Some churches have a Saturday evening service, or a particularly early service on Sunday morning, where the sermon is captured and delivered to the satellite campuses via an Internet-based file transfer system or via good ole' SneakerNet (delivery by foot). This provides a physical file onsite at each campus that gets played back when they are ready to start the sermon portion of their service. Others choose to stream the sermon live to each satellite campus for each service, so that every campus has a live delivery of the message—the chosen method for this feature.
Live streaming of the service is the most complex of the options. One difficulty is simply arranging for a reliable high-speed network connection for the high-bandwidth video stream from the transmitting campus to each of the satellite campuses. Another is coordination: do you try to ensure that each satellite campus is ready to start watching the sermon at exactly the same time as the transmitting campus, or do you implement a method to delay the video? And what about if you desire side-screen graphics/IMAG? Do you send a second video feed to each campus for the side screens, or do you try and run the side-screen graphics live at each satellite campus?
Transmitting the message
Legacy Christian Church in Overland Park, Kan., chose to do live streaming to each of its four campuses. To closely replicate the experience at the transmitting campus, they also wanted to transmit the side-screen images, which are image magnification (IMAG) close-up shots with graphics overlaid on top; this adds another level of complexity [to the process]. Because unlike straight graphic slides, which wouldn't likely be noticeable if the slide timing is off by a fraction, the IMAG stream needs to be perfectly synced to the main video to avoid distracting visual delay. Yet, Legacy wanted to give its satellite campuses some leeway in their timing, and not have to deal with making sure that they were ready for the sermon at the exact time it would start at the transmitting campus.
“Because of the programming design of the worship services, the receiving campuses could be anywhere from 15 seconds to three minutes behind the live broadcast,” explains Shane Rushik, executive director of technology for Legacy Christian Church. “That requires the ability to time-slip the incoming live video by pausing at the cue point and holding until the local site is ready for the broadcast, then hitting play to begin the transmission.”
Stark Raving Solutions, based in the Kansas City, Kan., area, suggested that Legacy look at the Harris Selenio line of encoders and decoders for the ability to encode multiple video streams into one IP network transmission. Legacy chose to move forward with the Selenio system, and started looking at technologies for time-slipping the video feeds.
“There are many products that can accomplish this time-slip,” says Rushik. “What makes the process complex is keeping the two video streams dead-on in sync. We looked at broadcast-quality video DDRs that had the ability of ingesting two video streams, and the cost to supply four campuses was over $150,000. This prompted a search for a way to accomplish the same ability to pause and cue the live video differently.”
The church wanted the satellite campuses to have some leeway in when to start the streamed sermon, but with two synchronized streams, the execution was more complicated than expected.
Through a little research, Rushik came upon a product from Pixelmetrix called DVStor. DVStor actually records the network IP stream itself—not the decoded and de-multiplexed video. As the network IP data is stored with no decoding, the video streams are by definition in the same sync-lock as they were when the stream was encoded. A DVStor server was installed at Legacy's transmitting campus, and each remote campus would have the ability to cue and start playback of the stored stream independently of each other.
At least, that was the theory.
Snags and solutions
On initial implementation, the church hit several snags. The DVStor remote control application did not allow the granularity of control that the churches needed to time-slip sometimes just a few seconds. And the Selenio system was not designed to create lip-sync accurate synchronization between the two video sources.
“On paper, the installation looked straightforward,” says David Buck, sales engineer for Harris Broadcast. “Encoding multiple streams of video is exactly what Selenio was designed for. However, when we realized that the second stream was a close-up of the first, and lip-sync level synchronization was needed, that was when we had an issue.”
The Selenio system was designed for broadcasters, who frequently need to multiplex two or more video signals into one transmission. However, the two signals are normally completely unrelated to each other, and there's no need for that tight a level of synchronization. “A television station may have three actual channels that they broadcast and need to transmit via IP to another location,” explains Buck. “However, the video content of the three channels aren't ever intended to be watched simultaneously in sync, and therefore the original Selenio product wasn't designed to provide that level of synchronization. We worked closely with [Rushnik] to add features on the decoder side of the system to lock the two decoders in time.”
The Pixelmetrix system has a similar issue, with the design originally intended for a broadcaster who might be delaying a program feed by an hour or two across time zones—not seconds or a few minutes. Rushik reports that the DVStor engineer also worked closely with [him] to implement a web browser-based interface to cue and pause the recorded stream at the level of granularity required by Legacy Church. Being an Asia-based company, the Pixelmetrix engineer would work through Rushik's night to fix bugs and implement features, and have a new release to try when Rushik arrived at the church the next day.
Over a period of several months, Legacy Christian Church, Harris Broadcast and Pixelmetrix were able to develop a system that met Legacy's needs for time-slipping and stability.
Over a period of several months, Legacy, Harris Broadcast and Pixelmetrix were able to develop a system that met Legacy's needs.
Then came the decision of where to locate the DVStor server. To reduce the needed upload bandwidth from the central campus, Legacy could have installed a DVStor server at each satellite campus, and had each campus record the IP stream separately. Or they could have located the server at an off-site data center, also reducing the overhead on any one campus. Or, they could go with the solution they decided upon, which was to locate one DVStor server at the transmitting campus and have it send out one IP stream of video content to each of the satellite locations, with each satellite campus able to time-slip the stream independently.
“We went with this solution over separate DVStor servers at each campus both to reduce cost [and] so that transmitting from any of the campuses would be possible,” Rushik says. “To transmit from another campus, all we need to do is move the encoders to the other campus and send the IP stream back to the DVStor server at the main campus. The playback process for the other campuses doesn't change at all.”
While this is the most cost-effective option, it does carry a larger amount of risk with it, because the only campus that will have the actual recording is the main campus. If the Internet connection should go down on later services, the satellite campuses will have nothing recorded locally to play back.
Of course, audio is also part of video-streaming the service to other campuses. “Selenio allows up to eight pairs of audio for each video program to be encoded in the stream,” explains Buck. Legacy Church therefore can transmit up to 32 channels of synced audio to the remote campuses with their two video streams.
“Currently, we only make use of four of the eight channels of audio available to us,” Rushik reports. “We send the pastor's mic, lead vocals, instruments, and drums all on separate channels so the remote campuses can adjust the levels to best suit their specific room and audience.” While the time of worship is handled by a local music team at each campus, sometimes a special song is done at the transmitting site and the remote campuses experience that through their video feeds.
With the standard eight TB of storage, the DVStor server can record up to 700 hours of 20 Mbps data. This is enough to archive over a year's worth of services at Legacy Christian Church.
To handle the streaming to and from the remote campuses, Legacy had to invest in the network infrastructure to handle the Internet traffic bandwidth. “Our main campus—the transmitting site—has a 40 Mbps fiber connection to the Internet,” states Rushik, “with each satellite campus having a 20 Mbps connection.” Currently, Legacy is sending a 12 Mbps feed to each of the satellite campuses.
“Because of reliability issues with the Internet service providers, we ended up switching to a point-to-point fiber connection with two of the campuses, which strangely enough was less expensive that using an ISP for the needed amount of bandwidth,” Rushik says. “The third location, utilizing a completely different ISP, continues to receive the 12 Mbps mux'd IP video stream (including both video sources) through the public Internet delivered with standard cable modems on the Comcast network. Amazingly, their reliability even through the public Internet is absolutely perfect.”
“Harris Broadcast and Pixelmetrix both recognized the importance and potential of the needs of houses of worship,” Buck adds. “And it was well worth the investment in working closely with Legacy Christian Church to implement a system that would meet their needs. [Rushnik] made two products better—ours, and Pixelmetrics.'”
