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Re: Code to create UIImage of waveform from audiofile?
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Re: Code to create UIImage of waveform from audiofile?


  • Subject: Re: Code to create UIImage of waveform from audiofile?
  • From: Paul Davis <email@hidden>
  • Date: Sat, 20 Mar 2010 10:14:23 -0400

On Sat, Mar 20, 2010 at 7:22 AM, Thomas Thiriez <email@hidden> wrote:
> In my experience, the API used for drawing the waveform is not the
> most important thing. You are just drawing a bunch of vertical lines.

if you look closely at the displays of waveforms in several bits of
audio software, this isn't always true. its certainly the cheapest and
most efficient thing to do but doesn't necessarily provide the nicest
appearance for some purposes.

> What is important is the data structure you use to keep the waveform
> in memory so that you can redraw it without having to read the whole
> file from disk every time.

affirmed. or more specifically, that you cache a suitable amount of it
in memory. if you're dealing with a 10GB audio file, keeping even just
the whole waveform image in memory for display purposes, let alone the
audio data itself, is not sensible.

"there are only two really hard problems in computer science: cache
invalidation and naming things" (Phil Karlton)

(this one falls into problem #1 :)

--p
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References: 
 >Code to create UIImage of waveform from audiofile? (From: Eagle Offshore <email@hidden>)
 >Re: Code to create UIImage of waveform from audiofile? (From: Tom Blench <email@hidden>)
 >Re: Code to create UIImage of waveform from audiofile? (From: David Duncan <email@hidden>)
 >Re: Code to create UIImage of waveform from audiofile? (From: Paul Davis <email@hidden>)
 >Re: Code to create UIImage of waveform from audiofile? (From: Thomas Thiriez <email@hidden>)

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