Streaming Forum: Building an HTML5 Video Workflow
20180227 StreamingForum HTML5 Streamroot Beavers
By Tim Siglin
Streamroot head of partnerships covers adoption of MPEG-DASH, AV1, CMAF, and several more acronyms
Erica Beavers, head of partnerships at Paris-based Streamroot, crystallized the challenges around HTML5 video workflows with this insight: "We often see roadblocks and delays in development by missing a component of the workflow," said Beavers.
Streamroot's technology is implemented client side, and Beavers said the company has offered professional services to help broadcasters make the transition from Flash Player-enabled players to HTML5 players. As a result, Beavers says Streamroot has a number of insights into the industry, including insights into codecs, formats, and players.
Codecs
Beavers notes that there have been two codecs in the last decade: AVC (H.264) and VP9. These two are being replaced, respectively by HEVC (H.265) and AV1.
VP9 can now be used with MP4, as part of the Common Media Application Format (CMAF). Its successor, AV1, had a hard freeze to its code in January but Beavers expects at least one year for hardware adoption.
"AV1 has a lot of supporters in the industry," said Beavers, "but it is not going to be as easy as many of us hope it will be."
Formats
The presentation then shifted to discussion of formats. About a year and a half ago, Apple announced that its HTTP Live Streaming (HLS) will support fragmented MP4 (fMP4) files in the form of the Common Media Application Format (CMAF).
This MPEG-ratified media format, which relies on the ISO Base Media File Format (ISOBMFF) commonly known as MP4 (MPEG-4 Part 12 or ISO/IEC 14496-12), relies on this fundamental baseline format of the MPEG-4 standard to allow for fragmented or segmented streaming of MP4 files using a byte-range addressing scheme.
CMAF is now MPEG-A Part 19, or ISO/IEC 23000-19, and was initially authored by both Apple and Microsoft: David Singer represented Apple and Kilroy Hughes represented Microsoft.
Apple is now part of the Alliance for Open Media, which is responsible for shepherding the AV1 codec, a successor for VP9, but Apple hardware support is not yet confirmed.
CMAF is intended to be codec-agnostic, meaning that it can be used with either AVC or HEVC and, potentially AV1.
"Players are starting to support CMAF," said Beavers, "but we've not seen a lot of implementations. This means you'll need to continue to support MPEG-2 Transport Stream segments for quite some time, since not all Apple devices can be upgraded in the field."
CMAF did not have its own digital rights management (DRM) which limited its adoption, but more recently the standard practice has been to rely on the Common Encryption Scheme (CENC) for DRM, since CENC provides a ready-made set of choices for MPEG-DASH workflows. FairPlay still needs to be used for most Apple HLS implementations.
Players
Beavers then shifted to video players, noting that the three key HTML5 players are hls.js, Shaka player, and the dash.js player supported by the DASH Industry Form (DASH-IF).
"That being said, we also have a number of off-the-shelf players," said Beavers, showing a page with almost twenty HTML5 players from a variety of online video platforms (OVP). "Some, but not all of them, use these open-source players under the hood and add their own features on top of them."
"We've seen that these players are starting to open up a little bit more, opening up the internals of their players to customization," said Beavers. "There's probably a ways to go there, but there's a demand from broadcasters not to have a 'black box' player that can't be customized."
On the mobile front, Beavers notes that building a mobile app builds on top of the native AV player in either Apple iOS or Google Android (which uses the Exoplayer open-source player).
FairPlay has been supported in the iOS web browser (Safari) since 2018, bu there is no media source extension (MSE) on iOS Safari 11.2, primarily since this is a Microsoft construct.
Chrome on Android now supports HLS natively, alongside an HTML5 player with MSE support.
"Performances are not radically different between the web view and native playback, at least with newer mobile hardware," said Beavers.
Beavers finished the presentation with some key trends. One of these trends, on the device side, is a push towards consistency.
"There's a push towards HTML5 and MSE-based systems across devices," said Beavers, noting that there's still a lot of fragmentation with smart TVs.
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