[Flac-dev] Re: nice idea

Miroslav Lichvar lichvarm at phoenix.inf.upol.cz
Mon Oct 7 13:03:02 PDT 2002

On Sun, Oct 06, 2002 at 04:41:02PM -0400, Hod McWuff wrote:
> OK, then how about a speculative approach?
> I'm going to go on these assumptions:
>   * linear predictive coding
>   * exhaustive search option
>   * lpc coding is capable of producing zero residual
>   * doing so is practical with a tiny block size
> Start with say, 64 samples (arbitrary), and compute a zero-residual LPC
> coding. Then use that coding to try and "predict" ahead into the
> un-encoded input stream. Compare against the actual input, and end the
> block where residual starts to show up.

Hmm, looks interesting for me. But i would rather use usual lpc with
order like 8 or so (your example -- i think residual will show up just
by 64th sample in most cases), and watch residual size for extrapolated
samples. What about something like this:

* compute lpc for small block (as you say, 64 samples for example)
* watch residual size for extrapolated samples by the block, in sample
  where starts significant changes, mark begin of a new block, estimate
  framesize of completed block
* start by the mark again, process this way few thousands of samples ahead
* join small blocks according to frame header overhead
* encode marked blocks

Miroslav Lichvar

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