Highwinds, Kaltura, Concurrent: Mobile Streaming Best Practices
Presenting best practices for streaming video to mobile devices, Highwinds, Kaltura, and Concurrent took part in a webinar hosted by StreamingMedia.com on Thursday, March 22.
The de facto standard for mobile video streaming is to use the H.264 codec in an MP4 container, presenting HD aspect in multiple bitrates, said Chris Bray, vice president of product management for content delivery network Highwinds, who spoke first.
Bray offered several tips to consider for best results, such as making sure keyframe alignment is consistent across bitrates. That way, when a viewer switches streams, the keyframes stay in alignment. He also advised turning off scene detection during encoding (it introduces irregular keyframes) and encoding audio in the same way for all the video streams.
The industry is moving toward HTTP streaming, said Bray, with the strongest adoption around Apple HTTP Live Streaming (HLS). Some are playing HLS streams in Flash. MPEG DASH is still on the horizon, he said. While many are looking at it, they haven't yet made a commitment.
Next up was Damian Rochman, senior director of product for online video platform Kaltura, who noted that mobile video traffic is surging. For publishers, mobile video comes with several challenges, such as supporting different codecs, presenting a unified user interface and experience across various platforms, fitting into publishing workflows, and providing content protection.
Publishers who want to target a variety of mobile devices need an automated workflow that transcodes video for all targeted devices. They should automatically serve the best encoding, offering multiple streams for adaptive video, such as high-, medium-, and low-bitrate encodes, Rochman said. Viewers expect the same experience on a mobile site as they get on a regular website.
Comparing mobile website and app experiences, Rochman noted that neither is inherently a better experience. Mobile websites don't offer real full screen viewing but do offer cross platform access, while apps give better control over the experience but require custom DRM support.
As for content protection, Rochman said that mobile video requires workarounds to safeguard video, such as token authorization, geo blocking, IP blocking, or chunking. Going with an app is a currently a better route for those offering premium content.
Exploring the workflow required to create adaptive video for mobile devices, Jim Denenny, vice president and general manager for online media solutions at Concurrent, defined steps for transcoding (the processor intensive heavy-lifting), transmuxing (done on-the-fly, able to be done in real-time), protection and policy (for monetization), and delivery (using an HTTP infrastructure and leveraging a company's existing investment).
While MPEG DASH could well make adaptive video delivery simpler in time, requiring only one format for delivery, there's likely to be an overlap period when publishers need to support four formats, Denenny said. Fortunately, all of them use H.264 video, AAC audio, and MP3 audio. The best practice, he said, is to create a single MPEG4, fMP4, MPEGTS source and repackage it on-the-fly.
During the question and answer session, listeners asked about latency in live video, how to support older mobile phones, and closed captioning on mobile devices.
The entire webinar, "Best Practices for Streaming to Mobile Devices," will be hosted online for 90-days and is free to view. Registration is required.
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