[linux-audio-user] Re: extract and mix

[Brad Fuller]

LinuxMedia wrote:

> Brad Fuller wrote:
> >>> I couldn't find a way to do this in ecasound, maybe there's a way to
> >>> do it. Here's what I want to do:
> >>>
> >>> Find the exact length of a audio file in ms. I think ecalength can do
> >>> this, I know it's not sample accurate, but I just need down to the
> >>> around 1ms. Maybe there's another option other than ecalength.
> >>>
> >>> Then, I want to extract a section of another file: at a specific
> >>> location in ms at a length of the file above.
> >>>
> >>> Then, mix that extracted segment with another file and save the
> >>> result to a new file.  How can this be done? I don't know of a
> >>> utility that can extract a specific length at a specific location 
> in ms.
>
> This should work...
>
> bash> ecalength LengthFile.wav
> LengthFile.wav: 9.083s           (0m9s)
>
> bash> ecasound -i:ExtractFrom.wav -y:(StartPosition) -t:9.083 
> -o:Extracted.wav
>
> bash> ecasound -a:1 -i:Extracted.wav -a:2 -i:MixWith.wav -a:1,2 
> -o:BothFilesMixed.wav
>
> Of course, this gets tricky if any of the files in question have 
> different channel counts, bit depths, sampling rates or are of 
> different file types. It still can be done, but there will be other 
> interm steps involved. But in a best case scenerio, the above should 
> work.
>
> Let me know if this how it went....
> Rocco
>
Thanks Rocco,
That's close to what Jeremy mentioned over on the ecasound list. I asked 
him, and I'll ask here: do you know who to find the closest zero 
crossing? in the extracted "from" file? That would seem to be a 
necessary step to prevent clicks.
brad