Re: Offline Rendering... still a thing?
Re: Offline Rendering... still a thing?
- Subject: Re: Offline Rendering... still a thing?
- From: Jens Alfke <email@hidden>
- Date: Wed, 05 Aug 2015 09:30:26 -0700
On Aug 5, 2015, at 12:39 AM, Matthew Pease < email@hidden> wrote:
The more detailed version is that I'd like to provide a Tivo style ability to seek in the recent history of a stream. I want to display the entire history of the stream as graph of the levels. So that the user can see where there is activity within the stream. The app would allow them to quickly jump to some point in the history.
Ah, you want a waveform view. I’ve implemented this by rendering to a low-resolution PCM stream (e.g. 8khz 8-bit mono) then running some simple processing on the stream to capture the maximum absolute value in every bin of x ms, where the value of x depends on the resolution you want for your display.
(The trickiest thing to work out was the conversion from raw amplitude to a volume level; I went with the cube root.)
—Jens
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