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

[jb at kdenlive.org]

On September 6, 2017 9:28:31 PM GMT+02:00, Harald Albrecht <harald.albrecht at gmx.net> wrote:
>Hi,

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?

First step is to play one of your audio file directly with mlt:
melt myaudio.wav

Then during playback, pause, seek and play. Does the fade also appear ? If it does we should open an issue in Mlt with an attached audio sample.

If it does not, it is probably related to the audio mix transitions we have in Kdenlive, and sharing a small audio sample would help us make some tests.

Regards


>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

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.