Re: [linux-audio-user] Stretching with very high accuracy

From: Nick Copeland <nickycopeland@email-addr-hidden>
Date: Fri Jun 09 2006 - 01:18:28 EEST

>From: Paul Winkler <pw_lists@email-addr-hidden>
>Reply-To: A list for linux audio users
>To: linux-audio-user@email-addr-hidden
>Subject: Re: [linux-audio-user] Stretching with very high accuracy
>Date: Thu, 8 Jun 2006 17:42:36 -0400
>On Thu, Jun 08, 2006 at 11:15:03PM +0200, Nick Copeland wrote:
> > What is the format of the files? Raw audio, WAV, etc? What is the rough
> > content - if the signal is constant than sample insertion is not easy
> > you may not have periods of silence. If the signal does have silent
> > then the solution may be a noise gate that inserts samples - this would
> > all but inaudible. There is no reason why this should not work from file
> > file with 'cat oldfile | <program> > newfile so should not need to have
> > lot in memory.
>Given the very small amount of drift (53 ms / hour), we're talking about
>inserting maybe 1 sample per 30000. I submit that nobody will notice
>if you just insert a copy of an adjacent sample, and if you
>want better than that, interpolation between two adjacent
>samples would be even smoother.

You dont think that there may be issues with sample insertion at regular
locations? They can become noticable as they are cyclic - I tried it with
SLab, and for a while with bristol before deciding it needed resampling.
Perhaps going half way would be to duplicate a sample at zero crossing
rather than during silence. This would be a little more random and hence
less noticable.

Perhaps somebody should just fix sox - its such a cool tool that a fix might
be in order. Is it still maintained? I also thinks sox had a few different
options for resampling (binary/quadrature?), perhaps it just needs a
different option for the algorithm?


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Received on Fri Jun 9 08:15:01 2006

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