Audio/Video Out of Sync
richard22j at zoho.com
Mon Aug 15 13:40:04 PDT 2016
>Sent: Monday, August 15, 2016 17:41
>Browsers use HDS so probably aren't affected. They are served by both
>Akamai and Limelight so are probably on the "current" system so the BBC are
> >probably packaging these streams themselves. I think iPads etc now use the
>HVF streams so again probably are not affected.
>Akamai is still a major part of iPlayer. Between it and Limelight they
>serve all the HDS, HVF (current HLS) and Flash streams.
The BBC blog I quoted last night
"The distribution model was the other thing we changed. This was a much
bigger deal. Switching from 23 separate files to a single multi-tracked
file. This single file is then reference to create all the media variants we
need to support the different combinations of ABR sets and distribution
protocol. As a result, we store a single media file and can have over 30
variant combinations derived from it. Each variant will offer tailored ABR
set in specific distribution protocol - for example, mobile phones connected
on Wi-Fi as HLS, or for desktop computers wanting HD with a Flash player.
"Our transcode workflow changed from creating and publishing separate
assets, to transcoding all the video and audio components and creating and
publishing a single asset also with data about all the variant combinations.
This provided new levels of flexibility that means we can create new
variants and distribute in new ways, without having to re-transcode media.
We can now just add or re-write data about all existing content and it can
work in a new way."
The blog is about a year old, and it does not say whether the changes had
already happened, were going to happen in three years time, were just about
to happen, or were going to happen about now, although it does seem to be
written in the past. When it does happen, or if it has already happened, it
seems likely that it will be more difficult to have errors in one stream
mode and not others.
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