[theora-dev] DC prediction

[Jonathan Fabrizio]

Le 25/03/2011 13:52, Benjamin M. Schwartz a écrit :
> On 03/25/2011 07:38 AM, Jonathan Fabrizio wrote:
>> * Truncate DC to a 16-bit representation by dropping any higher-order bits.
>>
>> But why dropping higher-order bits ?
> 1. In practice, this overflow does not occur.  A non-buggy encoder is very
> unlikely to produce streams that overflow because this would result in bad
> quality.
>
> 2. Checking for overflow (which occurs not at all or very rarely) would
> waste CPU time, because most processors do not have fast saturating
> arithmetic.
>
> 3. Theora is designed to be backwards-compatible with On2 VP3, so the core
> decoding algorithms could not be changed.
>
> --Ben
>
thank you for your response
J.F.