>
> Hello.
>
> My problem is noise in the background of the audiostream. Videostream is
> ok.
> Equal if record or view from /dev/video0 I hear noise in the background.
> When there is silence, the noise is softer.
> Contemporary with it I have almost clear sound on /dev/video24.
If /dev/video24 gives you 'good' audio without noise then the noise is
introduced by the compression step. What /dev/video24 gives you is
basically the audio just before it is compressed. Manipulating the audio
stream properties is the only thing you can adjust to try to improve the
situation.
Listening to the audio sample I have to say that I hear nothing wrong with
the first bit. The second part sounds like bad tuning to me, it is
definitely not something that the compression step can ever introduce.
Comparing /dev/video24 with /dev/video0 is a good way to determine where
the problem is.
>
> I thought it is the encoder, so I tried:
> 1)
> various options for tda9887: qss=0/1,adjust=0x1f/0x00
> (for adjust=0x1f the noise seems to be softer,
> but I am not sure if there is a connection)
This is related to tuning, not the encoder.
> 2)
> various options for ivtv: radio=0/1,buffers=(min-max)
Unrelated to audio.
> 3)
> various audio stream bitmask combinations (ivtvctl -c audio=bitmask)
> sampling,layer,compression,stereo,subbands,emphasis
Changes the audio compression. Some settings might introduce a slight
hiss, but nothing dramatic.
The cx25840 audio digitizer might also be involved, but only if you hear
the noisy audio from /dev/video24.
Regards,
Hans
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