any way to prevent filtering of low frequency sound (<300 Hz) ?

[Zihad Tarafdar]

I am trying to transfer low frequency sound acquired from a digital stethoscope via voice option but it doesn't seem to work. I don't hear any heartbeat sound in the other end. It seems the default audio codec filters low frequency sounds less than 300 Hz. So, is there any way to prevent filtering of low frequency sound which are less than 300 Hz? thanks 

Zihad

[Iñaki Baz Castillo]

WebRTC is about voice/video transmission (so its codecs are supposed
to handle well voice and video, but not other frequencies).

> --
>
> ---
> You received this message because you are subscribed to the Google Groups
> "discuss-webrtc" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to discuss-webrt...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.



--
Iñaki Baz Castillo
<i...@aliax.net>

[Philipp Hancke]

Disabling audio processing as described in https://groups.google.com/d/msg/discuss-webrtc/a1DsB_NKfUg/4UJd9Y-eFz0J might help. But more likely you'' need to move any processing to the local side and transmit the results via the data channel to avoid the voice-specific codec filters.

[Silvia Pfeiffer]

Hold on. Opus is supposed to deal with a broad range of frequencies. Maybe forcing the use of opus might bring an improvement?

Best Regards,
Silvia.

[Sergio Garcia Murillo]

At least in chrome, opus encoder is initialized for voip instead of application. So apart of recompiling it, I don't know of any way to change the mode.

Best regards
Sergio

[Johan Folke]

Opus does indeed support full-range audio, but you must turn off all processing as Philipp mentioned. To set Opus to "Music" mode you must also enable stereo. In the regular mono "Voice" mode Opus will filter the lowest frequencies, but nothing as severe as everything under 300 hz. I would guess that there is a gentle high pass filter applied to frequencies below 80 hz, which might still be a problem in your case, if there is only very low frequency content in the signal.

[Justin Uberti]

Try setting googHighPassFilter:false in your gUM constraints.

On Tue, Jan 6, 2015 at 11:54 AM, Johan Folke <johan...@gmail.com> wrote:

Opus does indeed support full-range audio, but you must turn off all processing as Philipp mentioned. To set Opus to "Music" mode you must also enable stereo. In the regular mono "Voice" mode Opus will filter the lowest frequencies, but nothing as severe as everything under 300 hz. I would guess that there is a gentle high pass filter applied to frequencies below 80 hz, which might still be a problem in your case, if there is only very low frequency content in the signal.