[MPlayer-users] Audio click when speed changed

[Reimar Döffinger]

On Sun, May 18, 2014 at 08:01:00AM -0500, Chris Crochet wrote:
> On Sun, May 18, 2014 at 3:08 AM, Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> wrote:
> > Sorry, I just can't hear it.
> > You should always provide full command-line and full MPlayer output.
> > It might be caused by some other audio filters you are using.
> ...
> > Well, I can offer a patch for scaletempo to resolve a theoretical
> > problem, but as said I can't hear anything that could be called a
> > click".
> 
> Thank you for looking into this.  Scaletempo doesn't appear to be the issue.

Well, I am not sure what is the issue. I think it is either somewhere
before it, or it is possibly both scaletempo and lavcresample.
Not that if you remove -af scaletempo changing speed is done by
changing sample rate, which is done by inserting/reconfiguring a
resampling filter.
Unfortunately I probably won't have time to debug and fix this properly
right now.
So instead I added a (not too bad) hack to scaletempo.
I am fairly confident that the issue should be gone now as long as you
use -af scaletempo.
Though I admit I only tested it with the only sample where I managed to
really notice the issue, and that was a trivial 1kHz sine.
But that one definitely came out 100% smooth through all speed changes.
That change is in r37204.

> Loading test1.wav in a sound editor, I was able to hear the clicks, then
> visually examine them.  It appears small portions (a few ms) of audio from
> a few seconds prior are being inserted into, or replacing, what should be
> playing.

Oh, I missed that part. That is some very interesting information.
I would have expected the issue would be some audio getting lost.
If it is indeed old audio coming in I might have to look at some other
places for the issue...
If I get time...