An increase in streaming capacity has driven OTT service providers to look for ways to reduce the cost of video streaming without decreasing the overall quality of experience (QoE). Through the latest streaming optimizations, video service providers can achieve significant bandwidth savings, while retaining exceptional video quality.
This article will examine the current state of the art in streaming innovations.
Table of Contents
The Evolution of Video Codecs
Moving to a new codec can dramatically reduce the bandwidth for streaming. Using HEVC, video service providers can save up to 40% bandwidth compared with AVC. AV1 reportedly outperforms HEVC (on some content), offering up to 30% bandwidth savings.
Launching a new codec will not address all devices.
Therefore, a “simulcast” mode needs to be implemented where some devices will use the old codec (i.e., AVC), others will support the newer codec (i.e., HEVC), and the newest devices will leverage the latest codec (i.e., AV1). The savings will only apply to a limited set of devices.
Table 1 shows what savings can be achieved using a new codec, assuming certain distribution of the codecs on all devices. The bitrates are normalized by taking 100 as the AVC bitrate reference.
|New codec savings||27%|
It is important to note that the HEVC device popularity evolves over time, location, and device targeted.
- In a recent session at the Streaming Media Connect 2023, Alex Zambelli of Warner Bros. Discovery mentioned that in the U.S. 70% of the targeted devices were HEVC capable.
- Comcast’s Alex Giladi stated that 60% are HEVC devices.
Compared with a 100% AVC scenario, bringing HEVC and AV1 will only reduce the total traffic by 27%, with AVC still having the 48% of the traffic, HEVC 49%, and AV1 only 3%.
AVC is still creating a bottleneck, generating a need for additional streaming optimizations.
Given the codec situation, video service providers may need to use other methods to decrease AVC bandwidth.
A well-known technique called content-adaptive encoding (CAE) can reduce the bitrate without impacting the quality. There is a general agreement that CAE on average, reduces the traffic by 40% for AVC and 20% for HEVC, with no savings for AV1 as no AV1 CAE has been demonstrated so far.
CAE brings the bitrate to a level that is very close to what HEVC achieves.
As a result, some operators prefer to deploy AVC and CAE instead of HEVC. Using CAE with AVC and HEVC reduces the overall bitrate by 48% vs. 100% in the AVC scenario.
For many years, AI has been used for optimizing video compression. Video service providers can take several paths using AI.
The first approach involves optimizing encoding parameters, similar to what CAE does. The savings is negligeable when CAE is used.
The second technique optimizes the encoding ladder, saving some bandwidth, but much more on the storage side. Storage will be addressed in a later section.
The third method is to dynamically change the encoded resolution in the same profile, in order to adapt to the content complexity. Results have shown savings between 20% and 50% depending on the resolution used.
The last technique is to dynamically change the encoded frame rate, resulting in about 5% to 10% bandwidth savings depending on the motion. Overall, video service providers can safely count on another 40% savings when using AI in addition to other practices.
Zero Rating Streaming
In some countries like the U.S., an agreement can be made between the mobile network operator (MNO) and the OTT service provider where the content consumed will not be accounted inside the quota and in return it can be throttled by the MNO.
The benefit is to reduce the entire traffic over a mobile network to SD resolution instead of delivering HD or UHD. Then SD AVC traffic is capped to 1.5 Mbps. Streaming 720p30 video would be in the range of 3 Mbps, meaning zero rating can save up to 50% of the bandwidth.
Note that this technique will decrease the QoE since viewers will now be watching SD instead of HD, but on mobile devices that level of quality is generally good enough.
CDNs, when running out of capacity, tend to reduce the profiles served to the clients. This situation is difficult to quantify, as no data is publicly available. But it’s akin to moving from an HD to SD profile, similar to zero rating. CDN throttling is more of an exception, while the zero rating is mainstream.
This technique, similar to zero rating, will reduce the QoE, although viewers agree that on a TV, HD content can be watched using a UHD screen with a good enough experience. SD is not watchable on an UHD screen.
Content orchestration is a natural evolution of zero rating or CDN throttling, as it provides a similar outcome, but it is performed automatically.
This type of streaming optimization first looks at the content popularity and then allocates more encoding resources to reduce the bitrate of high popularity content. The goal is to reduce traffic for popular content while preserving the quality and to relax the encoding resources of low popularity content, increasing traffic while preserving the quality.
Table 2 shows a content orchestration model for a streaming service where 20% of the content generates 80% of the traffic, and the derating factor that optimizes high-popularity content is 20%. For low popularity content it is at +20%.
|Content||High Tier||Low Tier||Total|
The model shows that 12% of the total traffic can be saved using such a content orchestration technique.
Bandwidth Reduction Without QoE Impact
The total savings that can be achieved using all of the above-mentioned techniques simultaneously, without impacting the QoE, is described in Table 3. The savings are calculated for a 100% AVC scenario.
|CAE + Codec||48%|
|CAE + Codec + Orch||54%|
|CAE + Codec+ Orch+AI||68%|
The savings that a major streaming service can realize from deploying a new codec plus CAE vs. a full-fledged approach with a new codec, CAE, orchestration, and AI) is 38%. Those gains could be achieved with the VVC codec; however it would require replacing the complete installed base of devices, an effort that could take 10 or more years.
Bandwidth Reduction with QoE Impact
There are additional ways to optimize traffic. Table 4 shows the device distribution, according to a 2019 Conviva report.
|Device||Share of Viewing Hours|
The table is derived based on connected devices including TVs, smartphones, PCs and tablets.
|Device||Share of Viewing Hours|
Looking at the table, one can calculate the traffic created for each type of device with an associated prediction of the traffic pattern. (See Table 5.)
|Device||Share of Viewing Hours||Resolution||UHD||HD||SD||Traffic/user|
|Hour of streaming (GB)||6.6||1.8||0.7|
|Original total traffic/user (GB)||1.9|
Next, video service providers can apply an optimization rule:
- Send only HD to TVs and PCs
- Send only SD to mobile devices (i.e., smartphones and tablets)
The traffic results are shown in Table 6, with the red cells highlighting the one now zeroed. The savings for each user is 25%.
|Modified total traffic/user (GB)||1.4|
According to Sandvine report global internet traffic volume increased 23% in 2022, due in large part to surging streaming video usage. As streaming continues to dominate viewing consumption methods, video service providers need tools to improve bandwidth efficiency and maintain outstanding video quality. Table 7 summarizes the different savings that can be applied depending on the starting point and the type of optimization used.
|Starting Point||No QoE Change||QoE Change||Total Savings|
|New codecs and CAE||38%||No||38%|
At best, starting from a 100% AVC situation and applying QoE reduction, video service providers can save 76% of the traffic. At worst, using a new codec and CAE video service providers can save 38% of the traffic without changing the QoE.
Thierry Fautier is the Managing Director of a new consulting firm, “Your Media Transformation” that helps executives in the Media & Entertainment tech industry to address new markets or execute in a more efficient way in existing markets. Fautier comes with a unique blend of market & technology knowledge, as he drove more than $400M at Harmonic while writing more than 30 papers at international conferences. Your Media Transformation is addressing current industry challenges and opportunities such as but not limited to: streaming optimization, FAST, CDN 2.0, Generative AI, and more.
Fautier has been the Founder-President of the Ultra HD Forum, a leading force in our industry that drove the growth of UHD for broadcasters, service providers and live OTT streamers.
In his previous role at Harmonic, Thierry Fautier drove major initiatives from a solution perspective : IPTV, OTT and UHD. He was also in charge of innovation and representing Harmonic in various standards and industry groups. Fautier was part of the team honored with the 2020 Technology and Engineering Emmy®️ Award for its pioneering work in AI optimization for real-time video compression. Fautier was named to TVB Europe magazine’s 2021 list of the "Top 25" people to watch in the media industry.