Video Plays Faster Than Audio

My Grandstream 3000 uses g729 and h264 connecting to a Asterisk 1.4.10.1.

[extensions.conf]

exten => 1,1,Answer()
exten => 1,n,Record(video:g729)
exten => 1,n,Hangup

exten => 2,1,Answer()
exten => 2,n,Playback(video)
exten => 2,n,Hangup

I am testing on recording some videos from my phone. When I try to play the file, the video seems to play much faster than the video. I tried recording my self counting with my fingers while saying the number. Indeed the video plays much faster than the audio.

I found a thread reg “audio plays twice as fast” and their solution was making sure that the audio is in 8khz sample rate.

Is there anyway to tweak/modify/configure asterisk to play the recorded video normally?

Is there something wrong with the way I recorded the video?

Are there any more information that I should be indicating?

Thanks

a very small number of people are viewing this thread. i assume that its not only me that is experiencing this. i just hope that somebody already have solved this. any help or clues on getting me on the right track on solving this will be greatly appreciated. thanks!

What you are noticing is a fairly common problem in video conferencing. Lip synchronization is actually quite difficult.

Companies who first tried video conferencing (Like PictureTel) learned that they had to delay the transmission of the audio because processing and compressing audio and video are very different. Audio is much simpler than video, and doesn’t need nearly as much work as video. Much of that compression/decompression is responsible for the lag that you notice on video conferences.

The problem probably isn’t in the Asterisk, but rather the phone. Make sure that you have the latest firmware for the phone.

A quick check of the release notes of the GXV-3000 on the Grandstream website shows that there were fixes associated with delayed video released this year.

Check here for details. grandstream.com/firmware.html

Its either I have misinterpreted your answer or you have misinterpreted my problem :smiley: Anyways, thanks for your reply :smiley:

If I understand it correctly, you are saying that there is a problem with sync of audio and video with GS. I wish thats the case, but my problem is the A and V starts the same time but the V ends quicker than the A because V plays much faster. Lets say if I were to record a clock (with a sec hand)and me doing a voice over for what second it is on the clock. I will record it for 10 sec. When I play it, I could hear my self saying the first second up to the last second. The video will also display the first second up to the last second but it will play it in just 5 seconds (noticing that the sec hand moves faster on the clock moves faster than it should. Meaning it played a 10 sec video for only 5 sec, its like FastForward + Play in a VCR, while playing the audio in normal speed.

Any tips?

My GS automatically updates for every 60 minutes :smiley:

The Grandstream website has some tips about configuring an Asterisk box to use a GXV-3000.

Click here for details: grandstream.com/pdf/AsteriskandGXV3000.pdf

Thanks for your reply dufus :smiley: !

Actually I have done that and GXV3000 to GXV3000 calls are great! I have tried it with two Asterisk server (connected via iax) and each phones has its own asterisk server. The 1st server is in the US while the other server is in the opposite side of the globe. Using G729/H264, the audio and video qualities are great!

The problem is when I try to play a recorded file using the dial plan I posted. I also recorded the file using the same dial plan. The video plays much faster than the audio.