What is Streaming or OTT?

Streaming or Over-The-Top (OTT) content is the live or on-demand delivery of video media via the internet. Unlike downloading, where a viewer must transfer a file completely to a computer or device before playback can begin, streaming allows the transmission and playback of media to happen simultaneously. When the streaming process begins, media data is received, and a limited amount of that data is stored in a temporary memory called a buffer. Once the memory buffer is filled, playback of the stream is initiated. As the media data is displayed it is typically discarded to make room in the buffer for the continued transmission of the stream. In effect, the buffer acts as a time delay and helps to ensure continuous playback of the stream in the event of momentary connection interruption. This process of filling and emptying the buffer is repeated until the end of the stream.

Benefits of Streaming Media

  • Instant playback:
    Media playback begins almost immediately after the stream begins to download, dramatically reducing wait times. Current streaming media servers also allow viewers to jump to any moment of an on-demand stream without downloading the entire file.
  • Live transmission:
    Immediate playback allows for live transmission of events such as sports, concerts, religious services, presentations, performances and more. While there is some nominal delay in the encoding, transmission and buffering process, the playback appears instantaneous to the viewer.
  • Viewing rights:
    Since the media data is not fully downloaded and stored on the playback device, it is more difficult to copy and pirate. The publisher of the stream has complete control over when and where the media content is available.
  • Storage requirements:
    Since only a small portion of the streaming media file is being stored at any one time, the amount of physical memory required is greatly reduced. This is ideal for mobile devices such as smartphones or tablets with limited memory.
  • Adaptive quality:
    Depending on connection speed between the media server and the playback device, the quality of the media stream can be increased or decreased to ensure smooth playback. Slower connections can still access content, albeit at a lower quality. If the connection speed is variable, that quality can adapt dynamically.
  • Video on Demand (VOD):
    Along with the streaming file, depending on the media server and CDN configuration, it is also possible to provide a video file download for on-demand or offline use.

Video Connectivity


When designing a streaming video delivery system, the considerations will include what type and how many cameras will be used, and how that video signal will be connected to the media server delivering the stream. Streaming directly from mobile devices has recently increased in popularity, but to achieve professional quality and production flexibility, dedicated camera systems are preferred. Higher quality cameras offer HDMI or SDI outputs that can be connected to a media server through hardware devices such as the AJA U-TAP with USB 3.0, the Io 4K Plus with Thunderbolt interfaces, or via direct plug-in PCIe cards like the AJA KONA line. There are also standalone appliances such as the AJA HELO that will encode and stream H.264 from an HDMI or SDI video signal, with simultaneous recording to a network share or removable media.

Content Distribution Network

To distribute a video stream from the media server, a Content Delivery Network (CDN) is required. Essentially, a CDN is a network of servers (commonly referred to as a cloud, with examples like Akamai, Facebook Live, Twitch, YouTube Live and Ustream) located around the world that deliver content via the internet. By having multiple access points, a CDN is able to connect viewers to a server closest to their actual location to reduce latency. A CDN designed specifically for live streaming further reduces latency and provides scalability by distributing the demand across hundreds, or thousands of servers. This allows streaming video content to be delivered to multiple viewers simultaneously without interruption, which is essential for professional applications.

Streaming Protocols


Depending on the CDN selected, they will support multiple video streaming protocols for distributing the media content. A video streaming protocol is an accepted method of breaking up the video file data into chunks, transmitting, and reassembling for playback. Although often confused, video streaming protocols are independent from compression codecs and file formats. They have no bearing on how the data is compressed or the container the data is wrapped in, rather they are the method of how the data is transmitted. The most commonly used are the following:

  • RTMP: Real Time Messaging Protocol (Flash)
  • RTSP: Real Time Streaming Protocol (Android, Blackberry, QuickTime)
  • HLS: HTTP Live Streaming (Android, Apple, QuickTime and HTML5)
  • Unicast: Point to point connection protocol
  • Multicast: Point to many connection protocol

Multi-Camera Switching


To increase the production value of streaming broadcasts, it has become a common option to design a switched multi-camera system. Switching between multiple SDI or HDMI camera angles and content sources has major advantages over a single camera or mobile device stream. The ability to switch between multiple sources provides a more dynamic visual experience, and with video switching applications like vMix or Telestream® Wirecast, adding graphics and effects is simple to implement. Connecting multiple SDI and HDMI sources is easily available through a Thunderbolt 3 video interface like the AJA Io 4K Plus, or via direct plug-in PCIe cards with the AJA KONA product line. Together, the switching application software and multiple input hardware act as a production switcher.

Recording & Archiving


Although streaming is the primary function of a streaming video delivery system, there is also often a requirement for the simultaneous recording of the stream for archiving. Recorded files are available for archiving or publishing as downloadable files for on-demand or offline playback. While the streaming file may be compressed at a low bit rate to accommodate bandwidth limitations, the recorded file is often stored at the highest possible quality for archiving. The recording capability can be designed into the media server, or for portable applications a stand-alone appliance like the AJA HELO can provide H.264 (MPEG-4/AVC) streaming and recording with independent quality settings to either internal removable storage or external and networked attached storage.

AJA Streaming eBook

In cooperation with AV Technology magazine and Sound & Video Contractor magazine, AJA has published “Streaming Video for Live Events”, an eBook of collected articles on the latest in streaming and OTT technology. The eBook features practical case studies of live event and house of worship applications, as well as commentary on the latest market and technology trends.

Download eBook

AJA Streaming & OTT Solutions

Simplify Your Live Stream with AJA Gear

Whether handling streaming for Broadcast OTT, live events, sports, concerts, houses of worship, video conferencing or corporate events, AJA develops tools that make it easy to capture and stream video live to audiences on-site and around the world.

BRIDGE LIVE: Real-Time Multi-channel H.264, H.265 and MPEG2


BRIDGE LIVE is a broadcast-quality, low-latency turnkey system for Remote Production (REMI), Multi-Channel Video Contribution, Remote Collaboration, Direct to Audience Streaming and Multi Bit Rate/Format Delivery.

Equipped with 12G-SDI I/O plus the power and flexibility to enable real-time bi-directional encoding, decoding and transcoding for critical UHD and HD workflows, BRIDGE LIVE is an essential part of any modern live video production toolkit. A compact and robust 1RU form factor with redundant power supplies and a three year warranty, means peace of mind even when dealing with the most demanding applications.

Whether facilitating remote production, two-way interviews, live event streaming, multi-cam backhaul, field contribution, program return, confidence monitoring, collaborative production, ABR ladder profiles to hand-off for OTT packaging, HLS input and output for local delivery, BRIDGE LIVE ensures simultaneous, secure and stable workflows whether over private lines or the public internet.

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HELO: Standalone H.264 Stream/Record Appliance

Stream, record and deliver high quality video with the push of a button using AJA HELO. Combining 3G-SDI and HDMI I/O, the intuitive device allows you to stream to a Content Delivery Network (CDN) and simultaneously encode or record H.264 to SD, SDHC or SDXC cards, USB storage, or network-based storage for archival or easy hand-off to clients and/or editorial. H.264/MPEG-4 encoding ensures bandwidth efficiencies while a web-based UI makes advanced setup and configuration simple. The latest firmware includes HLS streaming support for streaming to a range of iOS connected devices on a shared WiFi network, perfect for added visual content at an event, or extending the reach at a large facility for a more immersive experience.

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U-TAP: USB 3.0 Connected SDI and HDMI Streaming and Capture

AJA’s U-TAP HDMI and U-TAP SDI devices connect directly to Mac, Windows or Linux computers via USB 3.0, without requiring drivers. Streaming professionals simply plug into a computer, feed an HDMI or SDI output from a camera to the computer and stream using popular creative applications. Small enough to stash away in your pocket, the devices are ideal for remote production and support a wide range of uses from streaming to video conferencing and more.


USB 3.0 Powered HDMI Capture


USB 3.0 Powered SDI Capture

Click below to view the U-TAP 3rd party software compatibility chart.


Io: Thunderbolt Connected SDI and HDMI Streaming and Capture

Combined with Wirecast, vMix and other similar streaming applications, AJA’s portable Thunderbolt 3-equipped Io 4K Plus with bi-directional 12G-SDI ports and HDMI 2.0 I/O offers powerful streaming setups for a range of applications with support for SD all the way to 4K/UltraHD for the highest end streamed imagery. Multiple input options are ideal for switching between a range of sources for high quality switched streaming results.

Io 4K Plus

Thunderbolt 3 Connected 12G-SDI and HDMI 2.0 Capture

Io 4K Plus is the cutting edge of capture and output hardware available over Thunderbolt 3, offering a full set of professional video and audio connectivity with support for the latest 4K/UltraHD devices, High Frame Rate (HFR), High Dynamic Range (HDR) and deep color workflows. The power of Thunderbolt 3 enables Io 4K Plus to handle a wide range of formats from SD to HD, UltraHD and full 4K with frame rates up to 60p over both 12G-SDI and HDMI 2.0 with single cable simplicity, plus HDR 10 and HLG support over HDMI for emerging HDR workflows.


T-TAP Pro is the newest generation of AJA’s proven T-TAP, featuring the latest 12G-SDI and HDMI v2.0 connectivity for working with up to 4K or UltraHD 60p video over a single cable. This allows for easy output of deep color, high frame rate, SDR and HDR video to a wide range of pro and consumer monitors and devices, all at the highest 10- and 12-bit quality. T-TAP Pro is a compact, silent device that delivers next generation mobile monitoring capabilities to any supported Thunderbolt 3 enabled system.

Click below to view the Io 3rd party software compatibility chart.


KONA: PCIe Connected SDI and HDMI Streaming and Capture

The KONA family of PCIe connected I/O and Capture cards deliver a complete range of connectivity from SD to 8K. KONA cards have multiple inputs ranging from HDMI to 12G-SDI, and with an appropriate workstation, two or more KONA cards can be used in conjunction to further increase the number of video sources. The pairing of KONA cards with switching software applications like Wirecast, vMix and other similar streaming applications provides full production switcher functionality for multi-source streaming.


HDMI PCIe Capture Card for Multi-Channel HD or Single Channel UltraHD

KONA HDMI is an 8-lane PCIe 2.0 multi-channel HDMI capture card, with all of the quality and flexibility you have come to expect from AJA. 

Designed for the demands of multiple workflows such as gaming, streaming, VJ-ing, live events switching, vlogging, VR, post and broadcast, this powerful card boasts support for dual channel capture up to 4K/UltraHD 60p or four channel capture up to 2K/HD 60p. 

KONA HDMI is also supported by both the AJA SDK as well as Video for Linux®, making it a perfect choice for developers of multichannel HDMI ingest, switching, monitoring and communication solutions.


12G-SDI PCIe Capture Card for 8K/UltraHD2/4K/UltraHD/2K/HD

KONA 5 is a powerful 12G-SDI 8-lane PCIe 3.0 video and audio desktop I/O card with unparalleled features for handling everything from SD to UltraHD2, 2K to 8K with full 10-bit 4:2:2 and 4:4:4 sampling for fantastic image clarity and 12-bit support*. Bi-directional 12G-SDI ports are perfect for switching between multiple sources for live streaming needs. For HDR workflows, KONA 5 supports HDR 10 and HLG* for rich color delivery over HDMI.
*Application Dependent


HFR 50/60p 3G-SDI PCIe Capture Card for 4K/UltraHD/2K/HD

KONA 4 is a powerful 8-lane PCIe 2.0 video and audio desktop I/O card with unparalleled features for handling everything from SD to HD, 2K and 4K with full 10-bit 4:2:2 and 4:4:4 sampling for fantastic image clarity and 12-bit support*. Bi-directional 3G-SDI ports are perfect for switching between multiple HD sources for live streaming needs, or in combination can be used for a 4K/UltraHD stream. For HDR workflows, KONA 4 supports HDR 10 and HLG* for rich color delivery over HDMI.
*Application Dependent.

Click below to view the KONA 3rd party software compatibility chart.



Corvid HEVC is a 8-lane PCIe 2.0 video encoder card providing real time, low latency HEVC encoding at 4K, 1080p HD and lower resolutions. Development partners can use AJA’s powerful SDK to integrate Corvid HEVC directly into their Windows and Linux applications using a flexible API for a variety of use cases, including streaming up to 4K 60p.

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