Re: [ecasound] extract, mix and save questions

Jeremy Hall wrote:

>>>This is the second file, -y means offset into the file, -t says how long
>>>it should run.
>>>
>>>
>>thanks, jeremy.
>>At this point, foo2.raw is the extracted file that is 30seconds long,
>>right? I assume that you are saying that the file in step1 is 30sec long.
>>
>>BTW, Do you know if there is a way to have it start at the closest zero
>>crossing?
>>
>>
>>
>What is your definition of a zero crossing? If you would explain your
>task, I can help you figure out how to accomplish it.
>
>
When the waveform reaches zero -- the data is 0.
Cutting at an arbitrary point is bound to cut at a data point that is
non-zero and then when the extracted file is played back could create a
click.

>
>
>>>Next mix them down
>>>
>>>ecasound -a:1 -i source1.wav -y:1500 -a:2 -i foo2.wav -a:1,2 -o foo3.wav
>>>
>>>
>>I don't know why you used -y here. foo2.wav should be the length of the
>>first file (source1.wav). I guess the issue is how does ecasound mix the
>>two? does it bypass the WAV header and start at index 0 in the audio
>>data (I assume that it does). If that's the case, then wouldn't it be:
>>
>>ecasound -a:1 -i source1.wav -a:2 -i foo2.wav -a:1,2 -o foo3.wav
>>
>>Where source1.wav is the file in the first step: source1.wav and
>>foo2.wav should be the exact same length.
>>(also assuming there is a step before this that converts foo2.raw to
>>foo2.wav)
>>
>>
>>
>I used the -y flag after the first source to show you that you can combine
>some of the steps into one. You can even use ewf files and play segments
>like regions of a playlist (to use ardour terminology)
>
>The -t flag is a global chain operator and tells ecasound how long to run.
>The ewf filetype is powerful. If one aio-object (input) is shorter than
>the others, ecasound is supposed to feed a zeros loop so that you don't
>get uninitialized noise coming out of that chain.
>
>If you're trying to find a specific point in a track so you can precisely
>perform a cut, the interactive mode of ecasound is helpful because you can
>make it run up to the marker place you want and monitor with the -t flag
>to make sure you don't overshoot. At one time there was a buffering bug
>so that you'd get an off-by-one loop depending on your buffersize,
>annoying for sure, which is one reason I did the manual math method.
>
>
I need to run this in a script, so interactive mode would be out.
I'll have to read up on ewf files... I don't know what they are.

>If you're writing cd tracks, remember your filesize (minus wav header if
>you wish) must be divisible by 2352 bytes (4*44100/75)
>
>_J
>
>
>
>>>It is important to make sure you use the same srate and that you read
>>>through the requirements from going from mono to stereo etc--use the erc
>>>effect if you want mono in stereo mode.
>>>
>>>Is that what you want? NOTE ecasound does an implicit -ea:50 on each chain
>>>(because there are two, and 50+50 == 100) so you may need to adjust your
>>>coefficients during mixing.
>>>
>>>
>>>
>>>
>>That's good to know, and it's appropriate that it does that.
>>
>>
>>
>>>Hope this helps.
>>>
>>>_J
>>>
>>>In the new year, Brad Fuller wrote:
>>>
>>>
>>>
>>>
>>>>I couldn't find a way to do this in ecasound, but 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. I´d like
>>>>to have it sample accurate, or at least to the nearest zero crossings.
>>>>
>>>>Then, I want to extract a section of another file: at a specific
>>>>location in ms and at a length of the file above. I see that sox may be
>>>>able to do this using the 'trim" feature.
>>>>
>>>>Then, mix that extracted segment with another file and save the result
>>>>to a new file.
>>>>
>>>>How can this be done? Any ideas?
>>>>
>>>>thanks,
>>>>
>>>>brad
>>>>
>>>>

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Received on Tue Dec 20 08:15:04 2005