[Live-devel] Not able to send 50 RTP packets / sec to the mobile

[Mridu Kaura]

>Ross Finlayson finlayson at live555.com 

>Your file "test.amr" gets streamed correctly by both 
>"testAMRAudioStreamer" and "live555MediaServer".  In each case, 
>QuickTime Player is able to play the stream (from the "rtsp://" URL 
>OK).


Hi All,

In continuation to Rajat's queries related to streaming AMR Payloads, we( 
Me and Rajat) have observed the following and still unable to solve it:

For your information, we are using testAmrAudioStreamer to stream test.amr 
payloads. The complete RTP Code is working in a separate thread. We are 
using the ethereal to capture the frames exchanged between the Phone and 
the RTP Server.

We have observed that, In case the phone does not send any RTP packet, the 
rate of frames that we send from the RTP Server is as high as 2000 frames 
per seond.

In case when the phone also starts sending the RTP Packets, we have 
debugged the code and observed that the first frame sent (after the phone 
also starts sending RTP Packets) takes almost 50 mili seconds to be sent 
out.. Due to this all the next queued up frames are also getting delayed. 
We have also observed in the ethereal logs that the frames are sent 
sequentially as they are built (i.e their Sequence numbers are correct and 
the consecutive frames show  a difference of 160 in their time stamps. ). 
But  the issue is that frames are sent at a very low rate of 2 or 3 frames 
per second. However, the phone is sending the frames at  the correct rate 
of 50 frames / sec and we are required to send at the same rate in return. 


We have managed to control the rate of sending frames by incrementing the 
fPresenattionTime (in doGetNextframe in AMRAudioFileSource.cpp) with 2 
secs duration. With this change we were able to modify the rate of sending 
the frames at 1 frame every two seconds 

Ross has already tested "Test.amr"  and there was no issue found with its 
streaming.. In fact we are using the same testAMRAudioStreamer,cpp that 
Ross had used (i.e. without any modifications). 

Ross had suggested that this rate is achievable if Test.amr and 
testAMRAudioStreamer.cpp are correct. With the correct files we are unable 
to achieve this rate.  Kindly guide us in case we are overlooking 
something and also please suggest as to how we can acheive the rate of 
sending 50 frames per second while streaming AMR audio.

Regards
Mridu Kaura
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