[SoX-users] Adding silence to lossy files without additional loss/distortion

[Ron L. <ron...@te...>]

On 21/10/2011 23:08, Ulrich Klauer wrote, about the 'pad' effect:

>
> (NB. If you are using a lossy file format, such as MP3, the audio
> data will be decoded, then re-encoded in the process, possibly
> leading to a sound degradation.)
>

Is this always the case for either 'pad' at beginning, or 'pad' at 
end?  I would be happy just to pad either end, if it would avoid any 
further encoding losses.

Taking MP3 as an example, assuming that any re-encoding may introduce 
distortion - which I can understand - does padding at the end still 
rely on a file decode and re-encode process?

And, does a similar 'file decode and re-encode process' take place if, 
instead of 'pad', a 'concatenate' or 'sequence' command/effect is 
employed, eg to prepend or append a short 'silence' file (of 
equivalent bit and sample rate, as described in the Sox documentation)?

Ron