Thanks.  Actually I'll have both mono and stereo cases, but was asking
about the stereo case.  Of course I can split the stereo into two mono
files.  I was hoping to do it in one line, which was the real question here
-- the synth effect documentation says it can operate differently on
different channels but I couldn't figure how to make that work.

Jeff

On Mon, 8 Jun 2020 at 07:13, Dr. Thomas Tensi <t.tensi@gmx.de> wrote:

> Hello Jeff,
>
>
> you wrote:
>  > > [similar problem as amplitude modulating a sine wave]
>  > I want to produce a stereo tremolo by using the sine amod
>  > effect, out of phase on the left and right channels.
>
> I am not sure whether this can be done in one command, but you could
> modulate the channels into left and right mono versions and combine
> (merge) the file into a stereo file. I assume that your source is in mono?
> To paraphrase your solution:
>
> -----
> INFILE=rd73_064__E4_082.flac
> OUTFILE=x.flac
> tempfileLeft=left.flac
> tempfileRight=right.flac
>
> LEN=0
> OFFSET=0
> phaseLeft=0
> phaseRight=180
>
> # sox command fragments
> tremPrefix=synth $LEN $OFFSET
> tremSuffix=2 sine amod 0.5
>
> sox $INFILE $tempfileLeft  $tremPrefix $phaseLeft  $tremSuffix
> sox $INFILE $tempfileRight $tremPrefix $phaseRight $tremSuffix
> sox -M $tempfileLeft $tempfileRight $OUTFILE
> -----
>
> Is this what you wanted?
>
>
>          Best regards,
>
>                  Thomas
>
>
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