Re: Has anyone ever used `echos` or `chorus`?

Thanks to all for the input. I'll reply separately to the points in each.


On 05/02/25 19:13, Doug Lee wrote:

 >> 2) It is exactly the same as "echo" with different (and more) parameters
 > I thought it differed from echo in that successive echos created by 
"echos" are included in what is fed into
 > the next echo in the effect. This would indeed mean that inputs to 
second and subsequent echos are replaced,
 > as part of the function of the effect.

echos does this (you need fixed-width font here!)

    In--+--------+-------------------+-------------------->|   |
        |        |                   |           * gain-in |   |
    ____v___    _v_     ________    _v_     ________       |   |
   |        |  |   |   |        |  |   |   |        |      |   |
   | delay1 |  | + |-->| delay2 |  | + |-->| delayN |      | |
   |________|  |___|   |________|  |___|   |________|      |   | * gain-out
        |        ^          |        ^          |          | + 
|------------>
        |        |          |        |          |          | |         Out
        |        |          |        |          +--------->|   |
        |        |          |        |           * decay N |   |
        |        |          +--------+-------------------->|   |
        |        |                               * decay 2 |   |
        +--------+---------------------------------------->|   |
                                                 * decay 1 |___|

So yes, delay2in is (delay1out + In) but the net result is that
delay2out is (In delayed by delay2) + (In delayed by (delay1+delay2))
and these two are exactly equivalent:

sox_ng --no-dither in.au out.au echos .5 .5 1000 .5 300 .5
sox_ng --no-dither in.au out.au  echo  .5 .5 1000 .5 300 .5 1300 .5

and so on for 3 delays etc.

In fact, the test suite tests specifically that to test echo and echos
against each other. (I say sox_ng, not sox, only because that's
the only place it actually works!)

If the echo-in-series effect is in fact what you need,
it can be considered a syntactic shorthand, but I doubt that anyone
ever needs specifically that. There's nothing like that in the DSP 
literature
or in any other package that I know of.

 > Didn't know that either, but I do use the silence effect often,
 > and probably sometimes with unusual parameters - like durations of 0.

The more I hear of the silence effect, the more problems I hear it has.
I found out today that if you have audio that peaks midway at -1dB,
to remove everything after (or before) that peak, you have to specify
-3.95dB. -3.94 leave the entire recording intact.


 > my failure to weigh in before the "filter" effect was removed
 > because I subsequently tried to use the FM broadcast filter example 
out of the
 > manual only to find I didn't know how to replace that effect in the 
example.

I didn't know about that; I wasn't following SoX in 2011.
If it did something you needed it can probably be put back now
though I haven't even looked at what it did yet.

In general I am against removing stuff, or even making it work "better"
because someone on the other side of the planet will have used what
it does to create a piece of music or in a script or called from another
program, and changing/removing stuff is a great way to break other
people's work by remote control, without even knowing you're doing it.

For example, there are compositions written in Csound in the 1980s
that render bit-perfect with today's Csound the same as they did
when they were written under MS/DOS.

In my case, I wanted to test many different versions of SoX and
had to sniff the version numbers and select -2 and -c 2 acording
to how old it was. If they had kept honouring -2 as an alias,
even undocumented, it would have made thing easier.

Unfortunately there was a deprecation/removal frenzy some time

before 14.4.2 so it's a bit late now, but I would avoid another one.


     M



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