Streaming multicast G.711 RTP audio to Cisco IP phones

[netboy]

Have the new VLC 0.9.2 and am trying to make it multicast g.711 RTP streams to Cisco 7941/7961 IP phones.

I presently have the phones multicasting among themselves. And I can get VLC to decode a multicast RTP stream from a phone. But I have no success with streams from VLC to the phones. Here is the string I am using...

#transcode{acodec=ulaw,samplerate=8000,channels=1}:rtp{dst=239.239.239.240,port-audio=20480}

[Rémi Denis-Courmont]

AFAIK, downsampling and/or downmixing are broken in 0.9.2.

[jackalman]

Would an older version of VLC be able to perform this function? I am also looking at a way to multicast to cisco ip phones.

Any help would be greatly appreciated.

[Rémi Denis-Courmont]

Resampling might work with 0.8.6. But that version won't support streaming G.711.

[zaifox]

Anyone succeeded streaming G711?
I tried to do it as well, but no luck so far...

any help is appreciated!

Cheers
Kristof

[Rémi Denis-Courmont]

It works with 0.9. The audio source must be mono and 8000 kHz however.

[singer]

Where can I get 0.9 ? Thank you.

[singer]

I am currently using 0.9.8a. When you say it works only with 0.9, I assume that it does not work with 0.9.8a. So I thought I will download 0.9. I found the ftp archive and there are no windows executable for 0.9.
I need to stream RTP in G711 Mu law to a device. I used this with 0.9.8a

"C:\Program Files\VideoLAN\VLC\vlc.exe" --sout '#transcode{acodec=alaw,ab=64,scale=1,channels=1,ar=8000}:rtp{dst=mydeviceIP,port-audio=1250}'
and 0.9.8a on windows crashes right away

[Rémi Denis-Courmont]

I mean, it works with 0.9.0 onward.

[singer]

Thanks Rémi.

I tried it and got it working. It crashes if I use single quotes around --sout but double quotes took care of the problem. Thanks.

a) The audio quality is not great at the target device. It plays with some static. The problem is not with the target device since I could send it a G.711 Mu-law RTP stream from another source and it worked OK.

This is what I am using for a command line.

"C:\Program Files\VideoLAN\VLC\vlc.exe" filetoplay --sout "#transcode{acodec=alaw,ab=64,scale=1,channels=1,ar=8000}:rtp{dst=mydeviceIP,port-audio=1250}"

I tried with a 64kbit ( 8 bit, 8000 Hz ) G.711 recording. I can hear it but with the static.

b) But it does not seem to work with other Mp3 files that are in 64kbit bit rate. So what files can vlc stream out?

c) I want to get an internet stream/file ( with a HTTP URL ) and stream it out to my device. Is that possible with VLC? Please help me with the steps.

Thanks very much.

[collboy80]

My problem is that phones are not getting any stream from VLC. I don't have any error message in message windows. When I check the current status of the codec information (Tools----Codec information-------statistics), it showing 0 under stream sent packets.


Please help.

[pjain01]

I am also having the same problem.I wanted to do an rtp stream with G711u codec.but whenever I see in Wireshark I see the packets of payloadtype - 96 in rtp packets. Which I think should be 0 for G711u.
Can anyone help for streaming rtp packets ith codec G711u. Is it possible to do it on VLC ir is there any other tool avilable for doing that.

[jackalman]

I am trying to perform something on the flipside. I am trying to use a Cisco phone to multicast the G711 audio and buy/build a set top box to receive it over rca cables to a audio device. Any ideas if I can VLC can do this of if someone knows a STB that supports this?

thanks in advance.

[niwa3836]

Hi, I am too trying to get G.711 working correctly to Cisco phones, but the VLC code right now isnt working. I have a separate stream going and hopefully we can get VLC working correctly in the is area. Watch this space.

Specifically on your question on multicasting from Cisco IP Phones to RCA cables etc (and building a box), just for info (and sorry if sucking eggs here), it is possible to generally get the Cisco phone to mutlicast (use the RTPtxm xml command, might have the letters transposed). You can then use an a Cisco router with an EM card to receive the multicast with the correct levels. PM me if you need / want help in this area

[dparkinson]

Was there any resolution to this? My expectation is that I could take an audio stream in of any format and transcode it to G.711 ulaw for use with the Cisco IP Phone? Is this possible? It doesn't seem to work. When the input is a .au music on hold file, it sounds terrible and when the input is an MP3, I don't get anything. I've tried various transcode options etc.

Any feedback anyone can provide would be hugely appreciated.
Thanks in advance.

[niwa3836]

Sadly its not fixed, the VLC team dont seem to want to fix the problem at this time.

[Rémi Denis-Courmont]

The VLC team's job is to review and integrate patches from the community. If patches are not sent, they bugs won't get fixed. It's as simple as that.

[niwa3836]

Has anyone seen any updates as to whether someone has managed to fix this issue. I'll keep looking!

[boteman]

The VLC team's job is to review and integrate patches from the community. If patches are not sent, they bugs won't get fixed. It's as simple as that.

As the other thread revealed, this function depends on the library from the FFmpeg folks, so I don't know how that affects our ability to develop a solution.

Another fact revealed that these RTP packets are framed in 16ms bursts instead of the desired 20ms and it was suggested that the Windows low resolution clock at 16milliseconds was the reason. I have an executable (that I can not share, unfortunately) that plays files to a unicast address or i.p. multicast group in a mu-law 8000bits/second format and sounds as good as can be expected on an AudioMate 360 gateway that sends and receives such RTP streams. I ran this executable on this HP laptop running Windows XP (I'm typing on it now), so I don't think that the Windows low resolution timebase is the limiting factor in getting this to work. At least it doesn't have to be the limiting factor because the fileplayer worked as expected.
viewtopic.php?f=4&t=63667&p=279607&hilit=0.016#p229605

I am not a C developer, so I can be of little use in writing code, but I do have some resources here that might help a real developer. At the very least I can test on my stuff where I do contract work, since RTP streams are their bread and butter.

It seems that there is a demand for this ability as there are Nortel and Cisco phone systems out there that could benefit from it. I sure hope the community can come up with a useful solution.

[Rémi Denis-Courmont]

You can continue ranting about how useful the feature would be, how the VLC volunteer developers and the community are not solving the problem(s), and why you cannot fix the bugs yourselves.

Streaming to softphones is clearly a feature for professionnals and businesses. As an unpaid developer mayself, I have other priorities to occupy my free time. That would include VLC development for my own use-cases and/or the much larger and poorer chunk of the VLC user demographics: playback-only home users.