A growing trend in media production and broadcasting is the migration of video transport from dedicated infrastructure like SDI onto general-purpose IP networks. Factors driving this movement include the increasing capability of commodity networking equipment. Hardware vendors are producing 10, 25 and even 100-Gbit Ethernet hardware at volume, resulting in lower equipment costs. Broadcasters and producers are looking to leverage the reduced effort associated with maintaining a single network infrastructure. Additionally, using IP-based networking on premises makes integration of cloud resources more straightforward.
One thing to consider while designing your transformation is how to ensure a resilient, reliable delivery network for both on-premises and cloud-based workflows. IP networks are in general designed to deliver packetized data from point A to B reliably and efficiently. However, packet loss does occur from time to time. These losses, while negligible for most workflows, can cause visible impact to video. This is because video is usually sent via low latency protocols that often lack recovery mechanisms.
Historically, RTP with or without FEC (SMPTE 2022-1) has been a popular mechanism for delivery of video over IP networks, especially in the on-premises environment. FEC provides a level of redundancy to the video stream by sending additional data in parallel with the main video RTP stream. Depending on the configuration of the FEC matrix, it can be configured to protect against individual or consecutive packet loss, up to the limits of the matrix’s ability to rebuild the missing packets. It’s fast, and provides a reasonable amount of protection against packet loss or corruption. But as bitrates have increased and the number of devices handling packets en route have increased, even aggressive 2D FEC matrices are not always enough to guarantee error-free delivery from end to end.
What is SMPTE 2022-7?
SMPTE 2022-7 addresses these limitations by delivering two (or more) identical copies of the program from the source to the destination. To eliminate as many single points of failure as possible, these streams should use different network paths. At the destination, the receiving device can rebuild a single stream by selecting individual packets from one or more of the copies sent to it, a process called seamless protection switching. This means that a workflow can survive both a complete loss of one network path or one stream copy without any impact downstream. Additionally, the workflow can handle intermittent losses on either path, as long as both paths don’t lose or corrupt the same packet.
SMPTE 2022-7 can be used in many points along a video workflow. Some examples involving AWS Elemental Live include:
- SMPTE 2110 inputs/outputs
- SMPTE 2022-6 inputs
- Network Inputs (RTP-TS)
- Network Outputs (RTP-TS), including contribution to cloud workflows via AWS Elemental MediaConnect
- AWS Elemental Statmux communication
Setting up SMPTE 2110 inputs
The SMPTE-2110 input type provides for a primary and secondary interface for each SDP to allow for redundant sources to be combined in the input. The two interfaces must be different.
Here’s an example SDP for an input using 2022-7 without NMOS:
v=0 o=- 456221445 0 IN IP4 <ip address> s=AJA Lily10G2-SDI 2110 t=0 0 a=group:DUP 1 2 m=video 20000 RTP/AVP 96 c=IN IP4 <multicast ip/port> a=source-filter:incl IN IP4 <multicast ip> <source ip> a=rtpmap:96 raw/90000 a=fmtp:96 sampling=YCbCr-4:2:2; width=1920; height=1080; exactframerate=30000/1001; depth=10; TCS=SDR; colorimetry=BT709; PM=2110GPM; SSN=ST2110-20:2017; TP=2110TPN; interlace=1; a=ts-refclk:ptp=IEEE1588-2008:<mac address> a=mediaclk:direct=0 a=mid:1 m=video 20000 RTP/AVP 96 c=IN IP4 <multicast ip/port> a=source-filter:incl IN IP4 <multicast ip> <source ip> a=rtpmap:96 raw/90000 a=fmtp:96 sampling=YCbCr-4:2:2; width=1920; height=1080; exactframerate=30000/1001; depth=10; TCS=SDR; colorimetry=BT709; PM=2110GPM; SSN=ST2110-20:2017; TP=2110TPN; interlace=1; a=ts-refclk:ptp=IEEE1588-2008:<mac address> a=mediaclk:direct=0 a=mid:2
(highlighted text indicates presence of redundant feed)
NMOS IS-04 and IS-05 is now also supported if you are using AWS Elemental Live in an NMOS environment. When NMOS is used, only the interface values for each SDP are required.
For additional details on using NMOS with AWS Elemental Live, see Simplifying SMPTE ST 2110 Management with NMOS.
Setting up SMPTE 2110 outputs
Like TS outputs, the SMPTE 2110 output group offers two destination fields. Note that 2110 outputs must be assigned to interfaces on the 25-Gb interface, SMPTE 2110 support must be enabled for the interfaces used, and PTP must be configured.
NMOS support is available as mentioned for inputs. Again, the interfaces still need to be specified.
Setting up SMPTE 2022-6 inputs with 2022-7
If you choose the SMPTE 2022-6 Input type, two sets of fields are provided for use with 2022-7 compliant sources. You must specify different interfaces for the primary and secondary locations.
Setting up SMPTE 2022-7 network inputs (compressed TS)
As of version 2.17.3, AWS Elemental Live includes a new input type called SMPTE 2022-7 Network Input. Selecting this input type provides two Network Location Stream fields to complete. These can specify the network location, interface, and IGMP source. Note that only RTP sources are supported, and the two sources must be binary identical in order for the 2022-7 seamless protection switching to work correctly.
Setting up SMPTE 2022-7 network outputs (compressed TS)
Setting up 2022-7 outputs is simple in AWS Elemental Live, as the mechanism for doing so has long been a part of the product. Each TS output in AWS Elemental Live provides for two destinations. Both destinations will receive binary-identical streams. By configuring the output with the two destination URIs of the 2022-7 compliant destination, you have created the required output.
Using SMPTE 2022-7 with AWS Elemental Statmux
When creating an AWS Elemental Statmux cluster using AWS Elemental Live 2.20.2 or later, your video traffic is automatically configured with SMPTE 2022-7 seamless protection switching enabled.
SMPTE 2022-7 seamless protection switching is supported across a wide range of input and output protocols in AWS Elemental Live. You can leverage this capability to increase the reliability and resiliency of your IP-based workflows to either intermittent or longer-term network issues while still being able to use low-latency protocols, which often have limited error-correction capabilities.