[theora] Indexless interpolation search seeking code

Conrad Parker conrad at metadecks.org
Sun Apr 25 20:38:37 PDT 2010

On 26 April 2010 12:29,  <xiphmont at xiph.org> wrote:
>>> "An index is only marginally useful in Ogg for the complexity added; it
>>> adds no new functionality and seldom improves performance noticeably.
>>> Empirical testing shows that indexless interpolation search does not
>>> require many more seeks in practice than using an index would."
>>> I am keen to see seeking code which is almost as fast as seeking with an
>>> index. Is the code used in this empirical testing online somewhere or
>>> otherwise available?
>> IIRC that that quote dates from pre-Theora, and I assume it would relate to
>> Vorbis-only files using libvorbisfile.
> Actually, I just wrote that recently.
> Fast seeking in a generalized Ogg file is no different from the
> seeking implemented in libvorbisfile.  I hadn't written any such code
> (outside of vorbisfile) because I'd been told it had been implemented
> in liboggz/oggplay.  Is this not the case?

sure, but  you're looking at around 5-7 seeks for a random spot,
whereas you pretty much have 1 by definition with an index ...


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