AW: Re: Curious slow audio fade-in with certain USB audio card ... SDL-related?

[Harald Albrecht]

No, volume is fine, there is no automatic gain control in either the recording or playback paths. And according to the Steinberg documents there is no fader anywhere in hardware or the USB chip, just good old OpAmps. As I said, I don't see this behavior on Android, regardless of using the stock USB kernel driver or a dedicated driver that the recording app also offers.
That's why I'm thinking it is somewhere in the software audio chain, but I couldn't find any information related to automatic fading in ALSA and pulseaudio. I don't have any additional automatic fader program running.
And I notice that the fading seems to be related to Kdenlive closing and reopening the audio output channel some time after stopping and on start playing. I don't want to put blame on any part here, this is just my limited analysis at this time.
Best regards,Harald


-------- Ursprüngliche Nachricht --------
Von: alcinos <french.ebook.lover at gmail.com> 
Datum: 06.09.17  23:38  (GMT+01:00) 
An: Harald Albrecht <harald.albrecht at gmx.net> 
Cc: "kdenlive at kde org" <kdenlive at kde.org> 
Betreff: Re: Curious slow audio fade-in with certain USB audio card ... SDL-related? 

Hi,
Does the playback volume varies in time besides this fade-in on restarts ? For example, if you speak normally, then very quietly (or very loudly), and then normally again, is the volume equivalent for both periods when you speak normally ?

2017-09-06 21:28 GMT+02:00 Harald Albrecht <harald.albrecht at gmx.net>:
Hi,
here's a difficult question, I couldn't solve so far despite extensive research. Maybe someone here from devs/users can help?
Some weeks ago I got myself a Steinberg UR22mkII USB audio mic preamp+playback for recording voice overs. So far, I were using a more bulky Behringer 12chan USB audio mixwr with mic preamps.
I'm noticing a strange audio behavior when using the UR22mkII in Kdenlive, which I don't see in Audacity: whenever stopping playing the project timeline, and then a few seconds later restarting it, there's a 1s-2s clearly audible audio fade in. This doesn't happen with the Behringer. This fade in basically makes editing and arranging audio clips impossible. For reference, when I'm using the Steinberg UR22mkII with my Android tablet to record audio, there's no such unwanted audio fade-in, and playback immediately is at the correct level.
Could the unwanted fade be related to how MLT/Kdenluve use SDL?
Yes, my question may, erm, sound strange. But after checking drivers, aufio setup, et cetera, this is the best educated guess I can make at the moment. Maybe the devs can, erm, chime in?
Best regards, Harald

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