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Live-Switching and Streaming From Mobile Devices

The production studio in your pocket—also known as your smartphone or tablet—has a pretty good camera, cellular data or Wi-Fi connectivity, and maybe even external microphone input and HDMI output connectors. This article will describe two different categories of live streaming from mobile devices: self-contained streaming and multidevice synchronized streaming.

Where Do I Connect?

So where do you connect to share your adventure? Live-streaming options on popular online video platforms (e.g., YouTube) and social media sites (e.g., Facebook) are growing in popularity. They are becoming so popular, in fact, that one of the early entrants into the live-streaming mobile space, Meerkat, has pivoted away from the live stream. Other examples include Periscope, Ustream, and Twitch.

In addition, content delivery networks (CDNs) such as Akamai, Limelight, and Tulix, have live-streaming architectures designed to handle thousands or hundreds of thousands of viewers for your live-stream adventure.

Cue Talent on Camera 2

But what if you want to add a bit of professionalism to your adventure, using more than just the single on-device camera to livestream your adventure? If you want to choose between two live sources, you’ll need a video mixer of some sort.

Traditional video mixers such as Broadcast Pix or TriCaster used to require the multiple video inputs into the video mixer to physically plug in, either on analog or serial digital interface (SDI) cabling. These days, however, even the traditional mixers are adding some form of network interface.

Some mixers capture high-quality, low-latency, iframe-only images, while others are geared toward H.264 as an IP transmission, such as an IP surveillance pan-tilt-zoom camera. A few even are set up to receive M2TS packets, decoding the multiplexed audio and video back into baseband video, which is then synchronized across multiple devices.

In the world of truly pocket-sized mobile production, though, the need to rethink all that wiring has led to some fairly innovative solutions. A few products in the marketplace—most noticeably on the Apple App Store, although a few also support the Android OS—now allow multiple smartphones to act as wireless camera inputs into a tablet-based video mixer.

These wireless video mixer products share a few common themes.

First, connectivity between the smartphones and tablet occurs via Wi-Fi connection, which means that the cameras themselves have to be on the same local area network (LAN) but not necessarily in the same room. Some applications require a separate Wi-Fi access point, keeping the load of multiple Wi-Fi connections off the tablet that is performing the video mixing and streaming.

Second, the most robust apps are tablet-only apps. This has as much to do with screen real estate as it does with the need for the additional processing power found in most tablets. A tablet is more likely to have a quad-core processor and robust graphics processing unit (GPU) than the average smartphone, which lacks a GPU and often houses a dual-core processor only.

Third, most video-mixing apps also allow content stored on the tablet to be used as a pseudo-live source, cued up to play prerecorded content just like a traditional video mixer would play clips from an internal digital disk recorder (DDR).

Finally, a few of the apps will also allow remote feeds. This offers the ability to grab an IP surveillance camera’s H.264 video stream or an M2TS broadcast stream, the latter of which is then demultiplexed into separate audio and video streams.

Recording What You’re Streaming

For those have-to-relive moments, the ability to record the live-switched output from the wireless mobile video mixer is a necessity. Many video mixer apps have a record capability, but only a few have the ability to record content at a higher data rate than what is streamed out to the internet.

Switcher Studio (Figure 2, below) is an example of a mature video mixer product. Using the Record + Broadcast feature on the Switcher Studio iPad app, live-stream producers can record 1080p content directly to the iPad being used as the video mixer. This provides a final mixed copy of the streamed video, complete with transitions and cuts.

Figure 2. The Switcher Studio iPad app

To record directly to the iPad at 1080p and still stay within the boundaries of the iPad’s processor, the video-mixing iPad can’t be one of the four camera-input sources. To mix, stream, and record a two-camera shoot, you’d need three camera-equipped mobile devices: one iPad and two other iPads or iPhones.

Here’s where it really gets fun, though. The Record + Broadcast feature on Switcher Studio doesn’t just record the final output on the iPad used as the video mixer. According to the Switcher Studio website, it also “triggers a recording on each connected device so you have full-quality video from each angle regardless of any glitches or hiccups on the network.”

In other words, each device stores its own angle as a high-quality isolated camera recording. This is definitely a feature that will be of interest to those who want to fine-tune content after a live stream, using a nonlinear editor (NLE) such as Final Cut Pro, Premiere Pro, or iMovie on the Mac platform.

If the final mixed version, the one recorded on the iPad being used as a video mixer, is perfect, there’s not even a need to transfer the content to an NLE, as Switcher Studio offers direct upload of the recorded file to YouTube.