[Freeswitch-dev] Rare audio "clicks" inside mod_conference

[Peter Olsson]

Thanks for the tip - it got me thinking in the right direction. I think I've found it now, and I'm running my changed code in production for some testing. If everything looks good I'll post a patch on Jira after the weekend.

/Peter

-----Ursprungligt meddelande-----
Från: freeswitch-dev-bounces at lists.freeswitch.org [mailto:freeswitch-dev-bounces at lists.freeswitch.org] För Anthony Minessale
Skickat: den 15 augusti 2012 18:45
Till: freeswitch-dev at lists.freeswitch.org
Ämne: Re: [Freeswitch-dev] Rare audio "clicks" inside mod_conference

Add some debugging to the places in switch_core_io.c that do memset, maybe its from that.


On Wed, Aug 15, 2012 at 7:57 AM, Peter Olsson <peter.olsson at visionutveckling.se> wrote:
> Before anyone mentions it (since I'm usually one of those who does), I 
> will submit this to Jira, but I would appreciate some more input 
> before doing so
> :)
>
>
>
> /Peter
>
>
>
> Från: freeswitch-dev-bounces at lists.freeswitch.org
> [mailto:freeswitch-dev-bounces at lists.freeswitch.org] För Peter Olsson
> Skickat: den 15 augusti 2012 14:50
> Till: freeswitch-dev at lists.freeswitch.org
> Ämne: [Freeswitch-dev] Rare audio "clicks" inside mod_conference
>
>
>
> I'm not really sure where to ask about this, but I'll give it a try on 
> the dev-list for starters..
>
>
>
> I sometimes (very rarely, but often enough to want to find the cause) 
> get audio "clicks" in the audio stream on devices connected to a FS conference.
> I have samples from wireshark showing the problem. In L16 format it 
> seems there are a few bytes set to 32767 (max int16 value), that is 
> causing the actual audio.
>
>
>
> The strange thing is that when this occurs, there is actually no one 
> that sends this audio (but all members except one will get this audio, 
> so it has been put into the buffer by the member without the click), 
> so I'm starting to think if this is a generated packet inside FS, that 
> is not initialized correctly, or if the decoding from PCMA/PCMU to L16 fails for some reason.
>
>
>
> I've traced it down so far that I know how to handle it (at least work 
> around it), but I don't know how to reproduce it, and I don't know the 
> real cause. With the help of lots of debugging I've seen that this 
> occurs when a partial frame is read from a member (however, according 
> to wireshark, this partial frame was never sent over the network). We 
> have 8khz conferences, and the connected members use PCMA and/or PCMU, 
> so normally when audio from a member is appended to the audio buffer, 
> the length of the data is 320 bytes (I guess this is L16). When the 
> click occurs, I've seen that the datasize is only 160 bytes instead, 
> which would more indicate a undecoded PCMA/PCMU frame. And as I said, 
> there is no packet with half the payload size anywhere in wireshark, 
> so I'm not really sure where this is coming from. I've looked through 
> most of the code in switch_rtp.c and mod_sofia.c (that's related to RTP), but I can't really find any good reason.
>
>
>
> Right now I've added a check (if read_frame->datalen !=
> member->read_impl.encoded_bytes_per_packet), and when using this it 
> member->works as
> expected (at least so far - as I said, it happens rarely), but I guess 
> I might miss a frame of audio. I will try to look into this further, 
> but if anyone have any suggestions I'm open for ideas :)
>
>
>
> /Peter
>
> 
>
>
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--
Anthony Minessale II

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