PBS modernizes its video encoding workflow with AWS Elemental MediaConvert

Nonprofit broadcaster Public Broadcasting Service (PBS) is on a mission to serve Americans with trusted programming and resources that educate, entertain, and inspire. By building on Amazon Web Services (AWS), PBS is able to continually innovate while delivering high-quality broadcast and streaming content to more than 100 million viewers across 350 member stations and online, primarily on a publicly funded budget. Furthering its mission in 2023, PBS began a library re-encoding initiative using AWS Elemental MediaConvert, a file-based video transcoding service.

In evaluating approaches for the re-coding initiative, PBS had a few specific objectives in mind. The team wanted to optimize the encoding ladder to provide more flexibility in how content is delivered. They also wanted to improve video quality for viewers. Finally, PBS wanted to achieve these goals while also saving costs.

“For years we transcoded our videos for streaming using Apple’s HLS guidelines, which worked well but we ended up with a fixed, one-size-fits-all ladder. But given the wide-ranging complexity of PBS video offerings, we determined over time that this wasn’t the most efficient strategy,” said Matt Norton, PBS Digital Senior Director of Technology. “Our team found that using MediaConvert with Automated ABR (Adaptive Bit Rate) Configuration enabled, and especially the Quality-Defined Variable Bitrate (QVBR) feature, gave us more efficient encoding on a per-title basis compared to our previous approach. Overall, video quality is better, viewers can download content for offline playback in half the time, and streaming costs are much lower.”

Uncovering efficiencies

Along with adopting MediaConvert, PBS also opted to move to Common Media Application Format (CMAF) for packaging its streams and looked at ways to further compress videos using a multi-codec approach. The team conducted a comprehensive investigation that compared viewer device support and cost for each format. PBS ran extensive client testing, using Mux Data monitoring tools, from AWS Partner Mux, to get insights into video engagement and quality of experience (QOE). The PBS team also conducted manual testing for QOE analytics, with a goal of determining how much it could compress the video while maintaining visual quality.

In addition to improving playback performance and overall viewer experience, the new encodings reduce each video’s size. This has resulted in significant cost savings, since fewer resources are required to deliver video via the Amazon CloudFront content delivery network (CDN). Viewers on slower network connections can now stream at the highest quality and resolution. And with smaller file sizes, more downloaded content will fit on mobile devices for offline viewing, which is particularly useful for parents who want their kids to watch high quality educational content on an airplane or on road trips.

“We found that the biggest bang for our buck was simply turning on QVBR, keeping the AVC codec, and packaging with CMAF as a first step,” Norton shared. “Then, we had a decision to make – do we re-encode the entire back catalog and all new titles going forward or just start encoding new titles using this strategy?”

Mapping a plan

Using Amazon CloudFront to access logs and AWS Lambda for processing, the PBS team analyzed which shows, titles, and bitrates were actually being watched and calculated the associated costs for each one. With this information, they developed a hybrid strategy to determine what content warranted the cost of re-encoding. Based on the data, they decided to re-encode the entire Kids catalog—about 2,200 hours of content—along with select titles from their General Audience catalog that were the most watched. Since early 2024, PBS’s new encoding strategy has been applied to all titles added to the catalog. Under the hood, the PBS team also stood up new Amazon Simple Storage Service (Amazon S3) buckets and Amazon CloudFront distributions, cleaning their up backend infrastructure.

“Re-encoding the entire Kids library was a smaller one-time cost because of the size of the library. As a result, we’re seeing a more than 50 percent reduction in CloudFront streaming costs,” concluded Norton. “We’ve been more deliberate about which titles we’re re-encoding from the General Audience catalog, so those savings are smaller but growing. Overall, PBS viewers receive a higher quality of experience, and having our content on a common modern encoding workflow allows us to have more stability across platforms.”

Conclusion

In the end, encoding with MediaConvert improved the experience for viewers both in terms of visual quality and faster download times with smaller file sizes. For PBS, in addition to improved efficiency and significant cost saving, this approach allows it to consider adding features such as 4K and HDR content in the future to further delight its viewers.

Learn more about with the benefits of AWS Elemental MediaConvert and start encoding today.