Choppy sound - Githubissues

JvanKatwijk / qt-dab

Qt-DAB, a general software DAB (DAB+) decoder with a (slight) focus on showing the signal

http://www.sdr-j.tk

GNU General Public License v2.0

296 stars 61 forks source link

Choppy sound #254

Closed gvanem closed 2 years ago

gvanem commented 2 years ago

I've built DAB-Mini using MSVC and clang-cl on Windows This is a clip from The Rolling Stones "You Can't Always get What You Want":

http://www.watt-32.net/dx/DAB-mini-P6-Rock.mp3

The sound is choppy as hell and sounds like crap.

Captured using Audacity. Tuned to P6 Rock, F216 at 229.072 MHz. SNR approx. 20 dB. Got a sync after approx. 4sec. Which I believe somewhat is good. And BTW, that same station in Welle.IO gives excellent audio using the same RTLSDR stick (lock-in = 1 sec).

So there's some problem with PortAudio or something else.

I've tried different audio-output devices, but they all sounds like crap.
I tried building with or without a -D__MSC_THREAD__. No change.

Where can I start digging into this?

gvanem commented 2 years ago

I can add: The audio is equally awful in DAB-maxi. But I suspect this maybe is a libfaad issue since in DAB-maxi, it shows lots of these:

Warning: No standard extension payload allowed in DRM
Warning: No standard extension payload allowed in DRM
...

So, if my libfaad was built with -DDRM could it cause such choppy sound problems?

andimik commented 2 years ago

Ok, let my try on P6 in the next days. I can receive it as well.

In the past I have listened to RIKS only with dablin_gtk, that is why I might not have noticed that.

The parameters are 64 kBits stereo and HE-AAC v1, which is used in many muxes all over Europe.

andimik commented 2 years ago

https://github.com/AlbrechtL/welle.io/issues/314

I remember I had similar warnings when I wanted to play with DRMplus (which means https://de.wikipedia.org/wiki/Digital_Radio_Mondiale here, BTW).

gvanem commented 2 years ago

@andimik You said The hint on #314 (comment) did NOT help.

Meaning building libfaad2 with or without -DDRM is not the cause?

I built libfaad2 via vcpkg install faad2:x86-windows. Which is really this repo.

I might have to delete and rebuild it or try the libfaad in Welle.IO.

gvanem commented 2 years ago

I found the cause:

I built libfaad2 using vcpkg install faad2:x86-windows, which installed a $(VCPKG_ROOT)/installed/x86-windows/include/neaacdec.h.
But the old bundled header ../includes/backend/audio/neaacdec.h was shadowing my new one.

So, swapping the 2 -I paths solved it for both the compiler and the moc program. The audio is now perfect!

andimik commented 2 years ago

Oh, good. Thanks for clarifying that.