Re: volume extremely low when combining many files

[Erich Eckner <erich@eckner.net>]

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Hi Bob,

I think the problem is related to "dither". Two suggestions:
try disabling dither ("-D") in all but the last sox command and
try to minimize the number of "snippets" you combine, e.g.: put
non-overlapping sounds in one file in the first step. This way you will
end up with less dither-noise.

cheers,
Erich

On 22.09.2016 19:56, Bob S wrote:
>> When you say 'silence' do you mean no signal at all, so if you looked at
>> it in a waveform editor there would be no waveform at all, or do you 
>> just
>> mean very quiet (ie a small waveform)?
>>
>> What does the output of sox, with the  stat  and  stats   effects look
>> like for these files?   If you trim out one of the sections that you 
>> think
>> is silent, what do stat & stats say about such a section?
>>
>> What do stat & stats say about one of the result file's meant-to-be 
>> silent
>> sections?
>>
>> Personally rather than trying to do the whole thing in one command, I'd
>> suggest you try working in changing the level of just one or two of the
>> small files, and examine them then with stat & stats.  Then look at the
>> file you get if you mix those two files together, and see if you can see
>> what levels are changing.
>>
>> -- 
>> Jeremy Nicoll - my opinions are my own
> 
> 
> Thanks Jeremy.  
> 
> Well, I am using the ‘pad’ command to insert what I assume is absolute silence. 
> 
> I have not used stat & stats, I’ll have to read up on those.
> 
> Also, for this example, I am not even changing the volume of each individual sample/track.  Everything is at full volume.
> So say for example I have 4 sound effects being assembled (when really it is 100 — if I actually just have 4 then this doesn’t happen).
> Each effect is 1/4 of a second long and they are spaced along a two second gap. And say they are all actually the same sound:
> 
> / sound 1/ ………………………………………………………………………………
> …………………………/ sound 1/ ……………………………………………………
> ………………………………………………………/ sound 1/ ………………………
>  …………………………………………………………………………….../ sound 1/
> 
> So in my first loop I assemble each of those four tracks, using ‘pad’ to place them at the correct position along the whole soundtrack.
> Then in the second pass I mix them all together.  And for some reason all that padded silence is adding up to static noise.
> 
> I will do some more investigation and try the stats thing.  But theoretically ‘pad’ should just add absolute silence, right? Adding 100 tracks of
> it together shouldn’t add up to noise, should it?
> 
> Thanks
> Bob
> 
> 
> 
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