January 2020 Summaries

Apple has revised its HLS specification for delivering streams with low glass-to-glass latency, addressing concerns about the original standard's implementation and adoption barriers. The latest revision removes the requirement for HTTP/2 PUSH delivery of parts of media segments and introduces a new prefetch behavior signaled by a new tag in the HLS playlist - EXT-X-PRELOAD-HINT. This change makes Apple's LL-HLS specification more closely interoperable with MPEG DASH-LL, improving cache efficiency at CDN edges and potentially resulting in cost savings. However, challenges remain regarding bandwidth estimation in a browser and widespread adoption of the revised standard.

The use of HTML5 autoplay attribute for videos on webpages is not recommended due to browsers' aggressive blocking policy. Instead, developers should consider using video.play() in JavaScript, which returns a promise that indicates whether the autoplay was successful or blocked. If the promise rejects, a play button can be shown in the UI for users to click and start playing the video. Additionally, starting with the video muted increases the likelihood of autoplay working. Always ensure controls are accessible for the player.

Mux, a startup focused on video, shared their experience creating an advertisement for BART, San Francisco's underground transit system. They discovered that BART does not allow any code in ads and faced challenges when their ad featuring a terminal with blinking cursor was rejected. The company went through the process of redesigning the ad but ultimately had to put it on hold due to time constraints. Despite this setback, Mux used the final video for their homepage and plans to continue pursuing out-of-home advertising opportunities.

The article discusses subtitles and captions in streaming video, their differences, types of captions, and how they work in Mux Video. It explains that there are two ways to carry captions - in-band and out-of-band. In-band captions are contained within the video stream while out-of-band captions are delivered separately from the video stream. The article also talks about various formats for delivering closed captions and subtitles files on the internet, such as SRT, TTML, and WebVTT. It mentions that Mux Video currently delivers all its video over Apple HTTP Live Streaming protocol (HLS) and supports WebVTT format. The article concludes by discussing the mysterious three flags - AUTOSELECT, DEFAULT, and FORCED - used in HLS manifests for captions and subtitles.

The latest update from October 13, 2021, introduces caption support for live video streaming. This feature is not only compliant with FCC regulations but also enhances accessibility for users with hearing disabilities and extends the reach of content to international audiences by offering subtitles in multiple languages. Furthermore, it can drive user engagement as many viewers prefer watching videos without sound. The difference between subtitles and closed captions lies in the latter's inclusion of transcriptions of sounds like music or sound effects. To add these features to your video, simply send us the files alongside your video file. This feature is available for all Mux Video customers at no additional cost.