Audio/Video Out of Sync

RS richard22j at
Mon Aug 15 13:40:04 PDT 2016

>From: tellyaddict
>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
went on,
"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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