#408 crackling audio

[hollunder]

Hi. I noticed recently that audio files played in smplayer crackle, depending on dynamics it seems.
It's especially prone to crackling at the beginning of a file and when there are big changes in dynamics.

I also seem to hear a 'jump' in volume about 4 seconds into the file, accompanied by crackling if the file doesn't contain slence at this point.

The same files sound fine in plain mplayer.

Version: 0.6.9 (SVN r3447)
Using Qt 4.6.3 (compiled with Qt 4.6.2)

Using MPlayer SVN r31774

I tried disabling everything in the audio tab, to no avail.
When I disable software volume control the volume slider still works, and I'm not sure that's intended.
Also, I have no idea how to set what to let the audio pass unaltered, I can't set Max. Amplification to 0 and the volume slider to 100, which would have been an obvious way to do that.

I experimented with this using the jack output and .wav files I recorded myself.
There's nothing unusual about this file afacs:
$ sndfile-info sehnsucht.wav

Version : libsndfile-1.0.21

========================================
File : sehnsucht.wav
Length : 14899244
RIFF : 14899236
WAVE
fmt : 16
Format : 0x1 => WAVE_FORMAT_PCM
Channels : 2
Sample Rate : 44100
Block Align : 4
Bit Width : 16
Bytes/sec : 176400
data : 14899200
End

----------------------------------------
Sample Rate : 44100
Frames : 3724800
Channels : 2
Format : 0x00010002
Sections : 1
Seekable : TRUE
Duration : 00:01:24.463
Signal Max : 31129 (-0.45 dB)

Jack is also running at 44k1, so there should be no resampling happening.

I recorded a few seconds of the output of both smplayer and mplayer for demonstation purposes. I didn't match the levels, smplayer is louder, but the distortion can't have occured within jack and isn't in the original file (it was normalized to reach Signal Max : 31129 (-0.45 dB) and you can't hear it with mplayer, guess that's proof enough).

[hollunder]