Codec Session

  • Recovering from decode errors in the browser
  • What do people want to do?
    • Want a non-destructive failure
    • Want to keep source buffer
    • There is a range of different solutions
    • Browser masks the error
    • Want more data / metrics flowing back
    • Media error message - is that enough?
    • Rely on dropped frames
  • AV1?
    • Experience using AV1?
    • Bitstream is not finalized yet
    • Freeze at the end of Oct
    • Someone asked about a document for the bit stream
    • Real time performance of AV1? (parallelization)
    • Currently, 14 days for 1 sec of video
    • A lot of discussions about slicing
  • VP9?
  • How do we foster open codecs?
  • Typically adopted as codecs for the “open web”
  • Big CDNs? are sticking with MPEG2?/4
  • A lot is tied to hardware (with difference release/adoption cycle)
  • How do CDNs? handle video capabilities?
  • You get adoption through economics - needs to save people money
  • Need hardware support
  • HEVC - not adopted for web platforms
  • What doesn't Chrome allow HEVC even if hardware supports it? (Not all devices support it)
  • A lot of hardware decoders don't work according to spec (VLC on android for example)
  • Chrome has no plan to support HEVC
  • Firefox does not has a common pass-through decoder, have to develop a lot of custom pass-through decoders
  • VBR
  • People are allowing high peaks for VBR. How to allow players to handle the spikes?
  • If encoders can specify average deviation it would help the player
  • Players can also benefit from encoder declaring the peak
  • VP9? is working on VBR improvement to provide longer buffers
  • Another way to solve this problems is specifying video chunk quality for CBR
  • How does Dash handle stream change?
  • Keyframes need to match (this is specific for Dash.js)
  • Opus
    • Everyone loves Opus
    • EVS claims to be twice as efficient as Opus (half the bitrate)
    • Google is working on low-bitrate Opus (audio-only use case)
    • Per-title encode (content-aware encoding)
    • Multiple-pass encoding
    • Netflix gets 20% better than h264
    • Watch VDD Netflix presentation
    • Applicable for premium video content
    • n-to-n problems don't fit as well
    • Quality metrics
    • Create a set of metrics that characterize common mistakes
  • VMAF from Netflix (requires a reference)
  • UT Austin paper for reference-less measurement