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Re: [rtcweb] Transcoding Delay

Harald Alvestrand <harald@alvestrand.no> Thu, 16 January 2014 13:11 UTC

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Date: Thu, 16 Jan 2014 14:11:23 +0100
From: Harald Alvestrand <harald@alvestrand.no>
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Subject: Re: [rtcweb] Transcoding Delay
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On 01/15/2014 02:44 PM, John Leslie wrote:
> Stephan Wenger <stewe@stewe.org> wrote:
>> As for the delay introduced by the transcoding engine alone, let me note
>> that the single or two frame delay commonly attributed to transcoding is
>> realistic only for straightforward PPP type coding.
>    I agree that seems optimistic...
>
>> My understanding is that VP8, in its default encoder settings, uses
>> much more complex GOP structures for error resilience and coding
>> efficiency reasons. 

I have no idea where this idea comes from.

The dependency structures of VP8 when used in interactive mode are often
quite complex, with the purpose of minimizing recovery time when frames
are lost or damaged, but dependencies are always backwards-pointing;
there is no rearrangement of picture order.

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