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Re: Coreaudio-api Digest, Vol 5, Issue 67
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Re: Coreaudio-api Digest, Vol 5, Issue 67


  • Subject: Re: Coreaudio-api Digest, Vol 5, Issue 67
  • From: Dominic Feira <email@hidden>
  • Date: Wed, 27 Feb 2008 15:11:59 -0500

There are a couple of options.

1. Be pessimistic.
If you know the max bitrate use this to calculate the amount of time remaining.


2. Use a short running average.
Calculate the bitrate average of the audio output so far for the the last 10 seconds or so. Use that to calculate the remaining time. This is nice because it uses actual data instead of guessing and the user will get to see the duration remaining respond to the type of audio being recorded. For example if they are recording silence the duration remaining will go way up.


You could use just a bitrate average, but the duration remaining wouldn't respond to changes in the type of audio being encoded.

Dominic Feira / Code Monkey / Ambrosia Software, Inc. -- http://www.AmbrosiaSW.com

On Feb 27, 2008, at 3:04 PM, email@hidden wrote:

Hi,

I need this to calculate/estimate remaining recording time based on
available temp drive space.

I was just wondering if anyone has a good forecasting algorithm for
estimating the size of a compressed audio file.

The uncompressed PCM is trivial, as should the CBR case be. The
problem is mainly for VBR type files.

Any pointers and help will be greatly appreciated!


Thanks in advance,

\tommy

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