[opendtv] Re: (S) DTV adaptors available for less than 50 euros in France
- From: Tom Barry <trbarry@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 15 Sep 2005 22:49:48 -0400
> error concealment. But the bulk of the improvements
> are techniques gunning for better predictions. And
> the only reason to do better predicting is to
> increase GOP. I asked before: what else would that
> be for?
Better predictions means fewer residual error bits that have to be
encoded. This applies to a certain extent even on (ridiculously)
shorter GOP's.
But I haven't myself tested AVC efficiency on very short GOPs.
- Tom
Manfredi, Albert E wrote:
> Gary Hughes wrote:
>
>
>>And if AVC cannot offer significant compression
>>advantages without very long GOPs, it was a waste
>>of time that could have been better spent
>>tweaking MPEG-2. I do not believe this to be the
>>case.
>
>
> As in the case of 8-VSB's purported advantage at
> long distances, I'd like to see this one measured
> in real life before loudly proclaiming anything.
>
> The AVC effort was originally started primarily to
> serve very low bit rate interfaces, down around
> 64 Kb/s. It was then found to work well also at
> high bit rates, but at what price?
>
> When I go through and look individually at each
> improvement of AVC over MPEG-2, I see incremental
> improvements, e.g. in the entropy coding, compared
> with MPEG-2. And there's the deblocking filter for
> error concealment. But the bulk of the improvements
> are techniques gunning for better predictions. And
> the only reason to do better predicting is to
> increase GOP. I asked before: what else would that
> be for?
>
> I'm with Donald Koeleman on this. Take a look and
> see if you can find evidence of vast improvement
> in compression, except as relates to prediction.
>
> My SWAG is that at equal GOP lengths, AVC might
> save at best maybe 20 to 25 percent compared with
> MPEG-2. Pure SWAG, I admit up front.
>
> Others have mentioned this too, by the way. They
> tend to get shouted down.
>
> Bert
>
>
>
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