Server-side ad insertion (SSAI), often referred to as ad stitching, is the process of stitching video content and ads together on the server rather than on the browser (Client Side Ad Insertion). Videos and video ads originate in different places—videos typically come from a content delivery network (CDN) and ads from an ad server. (Video ads can also be served from CDNs, although content CDNs and ad CDNs often differ.) Then, video content and ad content are combined on-the-fly when people start watching videos. With server-side ad stitching, combining video and advertising occurs in the backend. For more information, see IAB Digital Video Advertising Glossary.
Note: In Sizmek Ad Suite (SAS), advertisers for audio ads use video and video interactive placements. SSAI is supported for audio in these cases.
In 2020, Streaming Media performed research highlighting that SSAI is the preferred method used by 45% of content producers, OTT operators, and IPTV operators, while legacy client-side ad insertion continues to decline (accounting for 24% of ad insertion models). For more information, see The 2020 Streaming Monetization Report.
According to Media Rating Council (MRC) requirements, traffic supplied based on the SSAI method should be deducted from net metrics (Impressions (Net)/Clicks (Net)) and reported separately as the Default Tracked Ads metric. MRC requirements are covered in detail in The Digital Video Ad Impression Measurement Guidelines. There is no support for viewability and uniques for SSAI as the measurement happens on the server and the measurement code has no direct access to the user watching the ad.
Sizmek Ad Suite (SAS) uses the following methods to detect SSAI for In-stream video:
Auto-detection based on IP addresses daily analysis from ad requests and VAST events. IP addresses, which belong to public/private data centers and with legitimate user agent values, are flagged as SSAI IPs. SAS reports traffic originating from the SSAI IP list into the Default Tracked Ads metric.
Note: IP addresses include end-user IP addresses that generate an unusual level of traffic within short time intervals; SAS suspects these addresses to be either SSAI servers or fraud.
IAB VAST macro SERVERSIDE added on ad request URL.
Important: Advertisers should confirm with publishers first if the SERVERSIDE macro is supported based on the IAB VAST standard. If the answer is not definitive, we encourage advertisers to contact the SAS Publisher Certification team to generate a test tag with the SSAI macro and do the required testing with the publisher before using it in a production campaign.
Values for the macro are explained in the following table:
All tracking pixels
VAST request URLs
0: Client fires request or tracking call without server intermediary.
1: Server-side ad insertion with client-side tracking. Server fires request or tracking call on behalf of a client. The client told the server to act on its behalf.
2: Server-side ad insertion with server-side tracking. Server fires request or tracking call on behalf of another server, unknown party, or based on its own decision, without an explicit signal from the client.
Value that indicates if a URL is requested from a client device or a server. This value may be set differently on the request vs. tracking URLs; the request may be made from a server (value of 1 or 2), while the tracking URLs may be fired from the client (value of 0). 0 is the default value if the macro is missing.
VAST tag with server-side macro:
Publisher's SSAI system should replace a macro with the actual value: 0, 1, or 2.
VAST URL ad request with server-side parameter set to 1:
SAS reports traffic with the SERVERSIDE macro values 1 and 2 into Default Tracked Ads.
Optionally, if the publisher uses a single ad stitching method across all VAST ad requests, the SSAI type can be predefined on the site settings in SAS. For more information, see Site Setup Settings. SAS reports traffic from sites marked as SSAI into the Default Tracked Ads metric.
For SSAI-detected traffic, there are several reporting limitations:
User identification based on 3rd party cookies does not work.
User geo-location based on IP address will not work, since the IP address comes from the server.
User device or operating system identification based on UserAgent may not work properly.
Due to these limitations, SAS applies limited General IVT (GIVT) filtering for SSAI-detected traffic. SAS applies GIVT IAB UserAgent allow/block lists, and filters external crawlers/bots and known IP test traffic. Accordingly, the Default Tracked Ads metric includes, by default, some level of unknown IVT traffic. SAS is actively exploring opportunities to expand GIVT filters for SSAI with client-side tracking and apply Sophisticated IVT (SIVT) techniques to SSAI traffic in the product roadmap.
The SAS Publisher Certification team started a BETA program with SSAI vendors to append the SERVERSIDE parameter automatically to VAST ad requests without requiring advertisers to generate the macro on their tags. The first results of the program are expected to be available by the end of November 2020. Based on the outcome of BETA testing, SAS will provide detailed instructions for publishers on how to activate the SERVERSIDE parameter with their SSAI vendor.
The following list is an example of SSAI vendors: Adobe Primetime, AdSparx, Amagi, Amazon Elemental (AWS), Bitcentral, Brightcove, Imagine, MostMedia, Switch, Verizon Uplynk, Vidillion, Yospace. The goal is to provide a list of tested SSAI vendors who can automatically append the SERVERSIDE parameter to VAST ad requests.
Based on auto-detection of SSAI, SAS lookback analysis for two weeks (September 26-October 9 2020) identified the top 20 sites that apply this method.
CBS Interactive US
Media Maximizer IN
MTV Networks US
OMG Trading Desk
Pandora Mobile US
The Trade Desk US
TUBI FKA Adrise
Viacom Networks US