DVB-S audio dropouts

[voodoosound]

Hi everyone,

when im playing dvb-s with my Hauppauge NOVA-HD-S2 dvb-s card, i do have audio dropouts every now and then. just short surges. and nothing in the terminal log.
It seems to me like its a buffering issue, but i have found nothing about it?
I dont even know if its a driver issue or vlc buffering?

any ideas?

thanks in advance
greets

[Rémi Denis-Courmont]

vlc -v should show audio warnings. It if's an audio driver issue, it should affect other players, and non-DVB inputs in VLC.

[voodoosound]

hi,
i didnt mean the alsa but the dvbs module

Code: Select all

01:05.0 Multimedia video controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder (rev 05) 01:05.1 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [Audio Port] (rev 05) 01:05.2 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [MPEG Port] (rev 05) 01:05.4 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [IR Port] (rev 05)

the -v option showed:

Code: Select all

[0xb3209abc] main audio output warning: output date isn't PTS date, requesting resampling (92235) [0xb3209abc] main audio output warning: audio drift is too big (196784), dropping buffer [0xb3209abc] main audio output warning: audio drift is too big (172784), dropping buffer [0xb3209abc] main audio output warning: audio drift is too big (148784), dropping buffer [0xb3209abc] main audio output warning: audio drift is too big (124784), dropping buffer ... [0xb3209abc] main audio output warning: resampling stopped after 20172496 usec (drift: -95873) [0xb3209abc] main audio output warning: buffer is 95873 late, triggering upsampling

[Rémi Denis-Courmont]

VLC does not use the hardware DVB decoder in any case, if that's what you mean.

It looks like something is wrong with the ALSA output. Make sure you're not using PulseAudio. Also, some crappy audio cards do not work very well at 44100 Hz; you can force VLC to output at 48kHz with: vlc --aout-rate 48000 (won't work if you have PulseAudio).

[voodoosound]

im using the pulseaudio module.
but if im playing movie thats not an issue.
im using the pulse-jack-sink for a little complex audio configuration...
is there any corrected pulse module? from source?
does anyone know the exact problem, perhapes i could have a look at it...


i tried the alsa module, but no change...

[Rémi Denis-Courmont]

To me, it looks like the output and the input are drifting. This is partly unavoidable for live input streams: the (broadcaster) timing is never going to be exactly in sync with the audio card clock. But if it happens a lot, then there may be something wrong downstream with the sample rate of VLC.

[voodoosound]

is there no possibility with some kind of buffer to overcome this?

at the moment im running a generic kernel, could the realtime kernel be a solution?

[a-slack]

Try with --dvb-caching 1000 or more, its value by default is 300 ms.

Through the GUI: Advanced Settings > Input / Codecs > Access modules > DVB > "Caching value in ms"

[voodoosound]

Yippie! that was the option i was looking for...

thank you!!!