Delay in Audio

[Hassan Choobin]

Hi
I've installed BigBlueButton 0.80 on the following address:
https://code.google.com/p/bigbluebutton/wiki/InstallationUbuntu

I've installed it on a dedicated server with the following specifications:
HP DL380 G4
RAM: 12G
CPU: 2 * Dual-Core Intel Xeon Processors

speed of my network is 1g and equipment of my network is Cisco.

I have a problem with audio.
there is 2 second delay when i use microphone for speaking.
i have not this problem when i use mouse and webcam.

What is the problem?

Sorry for my poor English language.

[Fred Dixon]

Hi Hassan,

There's lots of information in the FAQ related to audio.  See

  http://code.google.com/p/bigbluebutton/wiki/FAQ#Why_is_there_a_delay_in_the_audio_when_I_use_VoIP?

and

  http://code.google.com/p/bigbluebutton/wiki/FAQ#Why_is_the_audio_not_synced_with_the_video?

Glad to hear you've installed it in a dedicated server -- that's the recommended setup for BigBlueButton.

Most servers have a similar delay.  For example, you can open two web browsers and log into 

  http://demo.bigbluebutton.org/

from each, join the audio, and mute yourself in one of the browsers.  As you speak, your audio packets are going from one browser to the remote BigBlueButton server and back in the other.  You'll hear about a two second delay in the audio.  Try it and compare with your setup.

As the developers, we would like there to be no delay in the audio ... and we are always looking to improve the audio in future versions.

Regards,... Fred

-- 
BigBlueButton Developer

http://bigbluebutton.org/
http://code.google.com/p/bigbluebutton

BigBlueButton on twitter: @bigbluebutton

--
You received this message because you are subscribed to the Google Groups "BigBlueButton-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to bigbluebutton-...@googlegroups.com.
To post to this group, send email to bigblueb...@googlegroups.com.
Visit this group at http://groups.google.com/group/bigbluebutton-dev?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
 
 

[Hassan Choobin]

Thank you for your answer.

in the above link is said:

Currently, the audio and video in BigBlueButton go through two separate different systems: the audio goes through FreeSWITCH, while the video goes through red5.

For the video, red5 does not do much with the video packets -- it just re-broadcasts them to all the clients current subscribed to the video stream. It's basically a straight pass through of the packets.

For audio, the voice packets have a longer route to take.

Here's a breakdown of the path for the audio packets from your BigBlueButton client when using VoIP. When you speak, your audio is transmitted by the BigBlueButton client to red5 using speex codec. It is then transmitted by red5 to FreeSWITCH (via red5phone), then FreeSWITCH mixes in the audio, then the resulting audio stream is sent back to red5phone (via SIP), and transmitted back to the client.




I don't use the VoIP.
It is possible that I do not use FreeSWITCH for solve the problem.
If this is the right way how to do it?


Thank you for your attention.

[Federico Boerr]

This is a great question, I'd also like to know if it makes sense and if it's possible to omit that step.

Sent from my iPhone

[Chad Pilkey]

If you want to use the audio in BBB you have to use some sort of audio mixing software to cut down bandwidth requirements. If you just re-broadcast each of the audio streams individually you would have really high bandwidth requirements in meetings over 5 people.

[Federico Boerr]

Hi Chad,

This raises some questions to me that you have probably answered them many times.

Is there one video stream for each participant who shares video?

Don't video streams consume more bandwidth than audio ones?

I would expect audio stream bandwidth usage to be a tenth part of the video ones. 

Thanks,

Federico

Sent from my iPhone

[HostBBB.com]

Fredirico

Quoted From http://code.google.com/p/bigbluebutton/wiki/FAQ

For example, if you have a room with 5 users, each sharing their
webcam, then the you can calculate the bandwidth usage as follows:
•Y = 30-50 Kbytes/sec; let's assume 40 Kbytes/sec on average
•W = amount of webcams that are streaming
•U = amount of users that are watching

For calculations:
•server incoming bandwidth: W*Y
•server outgoing bandwidth: W*(U-1)*Y (minus one since a broadcaster
does not have to subscribe to his own stream)


For example, with 5 users in a room with 5 webcams streaming, the
bandwidth calculation is as follows:
•in: 5*40 = 200 Kbytes/sec incoming bandwidth needed to the server
(e.g. 1.6 Mbit)
•out: 5*(5-1)*40 = 800 Kbytes/sec incoming bandwidth needed from the
server (e.g. 6.4 Mbit)
•Total traffic used after one our: 60 mins*60 secs*(200 + 800) = 3.6
Gbyte traffic per hour

If you'd have a typical classroom situation with the presenter
broadcasting their webcam to 30 remote students, the calculation is as
follows:
•in: 1*40 = 40 Kbytes/sec incoming (e.g. 0.32 Mbit/sec)
•out: 1*(30-1)*40 = 1160 Kbytes/sec outgoing (e.g. 9.3 Mbit/sec)
•Total traffic used after one hour: 60 mins*60 secs*( 40 + 1160) =
4.3


Regards
Stephen
hostbbb.com

On Feb 27, 6:14 am, Federico Boerr <federicobo...@gmail.com> wrote:
> Hi Chad,
> This raises some questions to me that you have probably answered them many times.
>
> Is there one video stream for each participant who shares video?
>
> Don't video streams consume more bandwidth than audio ones?
>
> I would expect audio stream bandwidth usage to be a tenth part of the video ones.
>
> Thanks,
> Federico
>
> Sent from my iPhone
>

> On 26/02/2013, at 13:59, Chad Pilkey <capil...@gmail.com> wrote:
>
>
>
>
>
>
>
> > If you want to use the audio in BBB you have to use some sort of audio mixing software to cut down bandwidth requirements. If you just re-broadcast each of the audio streams individually you would have really high bandwidth requirements in meetings over 5 people.
>
> > On Tuesday, February 26, 2013 6:11:15 AM UTC-5, Federico wrote:
>
> >> This is a great question, I'd also like to know if it makes sense and if it's possible to omit that step.
>
> >> Sent from my iPhone
>
> >> On 26/02/2013, at 05:52, Hassan Choobin <choob...@gmail.com> wrote:
>
> >>> Thank you for your answer.
>
> >>> in the above link is said:
>
> >>> Currently, the audio and video in BigBlueButton go through two separate different systems: the audio goes through FreeSWITCH, while the video goes through red5.
>
> >>> For the video, red5 does not do much with the video packets -- it just re-broadcasts them to all the clients current subscribed to the video stream. It's basically a straight pass through of the packets.
>
> >>> For audio, the voice packets have a longer route to take.
>
> >>> Here's a breakdown of the path for the audio packets from your BigBlueButton client when using VoIP. When you speak, your audio is transmitted by the BigBlueButton client to red5 using speex codec. It is then transmitted by red5 to FreeSWITCH (via red5phone), then FreeSWITCH mixes in the audio, then the resulting audio stream is sent back to red5phone (via SIP), and transmitted back to the client.
>
> >>> I don't use the VoIP.
> >>> It is possible that I do not use FreeSWITCH for solve the problem.
> >>> If this is the right way how to do it?
>
> >>> Thank you for your attention.
>
> >>> On Wednesday, February 20, 2013 6:00:25 PM UTC+3:30, Fred Dixon wrote:
>
> >>>> Hi Hassan,
>
> >>>> There's lots of information in the FAQ related to audio.  See

> >>>>  http://code.google.com/p/bigbluebutton/wiki/FAQ#Why_is_there_a_delay_...
>
> >>>> and
>
> >>>>  http://code.google.com/p/bigbluebutton/wiki/FAQ#Why_is_the_audio_not_...

> >>>>> For more options, visithttps://groups.google.com/groups/opt_out.

> >>> --
> >>> You received this message because you are subscribed to the Google Groups "BigBlueButton-dev" group.
> >>> To unsubscribe from this group and stop receiving emails from it, send an email to bigbluebutton-...@googlegroups.com.
> >>> To post to this group, send email to bigblueb...@googlegroups.com.
> >>> Visit this group athttp://groups.google.com/group/bigbluebutton-dev?hl=en.

> >>> For more options, visithttps://groups.google.com/groups/opt_out.

[Federico Boerr]

Thank you very much Stephen.

For large classes, webcams are suggested to be turned off to avoid saturating the bandwidth and audio streams need to be merged as Chad suggests.

But for smaller groups, or one-to-one rooms, that are NOT using VoIP, skipping FreeSwitch may avoid the audio delay.

This leads us to the origina's thread question posted by Hassan:

It is possible that I do not use FreeSWITCH for solve the problem.
If this is the right way how to do it?

Thanks,

Federico

[Richard Alam]

Hi Federico,

On Wed, Feb 27, 2013 at 8:42 AM, Federico Boerr <federi...@gmail.com> wrote:

Thank you very much Stephen.

For large classes, webcams are suggested to be turned off to avoid saturating the bandwidth and audio streams need to be merged as Chad suggests.

But for smaller groups, or one-to-one rooms, that are NOT using VoIP, skipping FreeSwitch may avoid the audio delay.

This leads us to the origina's thread question posted by Hassan:

It is possible that I do not use FreeSWITCH for solve the problem.
If this is the right way how to do it?

The audio delay isn't incurred in FreeSWITCH. The time it takes to mix the audio is very small. The delay is in the echo cancellation (~1-2sec) in the Flash player.

Then if you have a slow connection or lossy connection, the transmission might add more delay.

Richard

--
-----
BigBlueButton Developer
http://www.bigbluebutton.org
http://code.google.com/p/bigbluebutton

[Federico Boerr]

This answers my question, thanks Richard.

I thought FreeSWITCH would add more time.

In my particular case, there is just a small delay in the video and audio.

Will try it without the echo cancelation and see how it works.

Thanks,

Federico