Friday, April 18, 2008

Audio and Video Port Problem in Audio Testing

RTP AMRTesting :
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1.I combined the multiple RTP packets in to a Single packet and passed it to the AMR Paser application;
2.Next added the AMR file extension and AMR start codes and try to play it with QT Player;
Created AMR file is wroking with QT Player; It is working.

3.Pls kindly check the Market Bit of the RTP header format;

if we are sending the audio and video thru INVC transcoder,I printed the RTP packet Number as follows:
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 60, Buffer size = 1389, Marker = 0
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 61, Buffer size = 1389, Marker = 0
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 62, Buffer size = 1389, Marker = 0
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 6, Buffer size = 28, Marker = 128
RTP packet Number = 63, Buffer size = 1389, Marker = 0

ffmpeg sends amr audio to RTP.I got the following:
RTP packet Number = 3, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 3
RTP packet Number = 4, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 4
RTP packet Number = 5, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 5
RTP packet Number = 6, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 6
RTP packet Number = 7, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 7
RTP packet Number = 8, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 8
RTP packet Number = 9, Buffer size = 1389, Marker = 0 HSB = 0 , LSB= 9


while sending audio and video we have the problem;One more thing if we send audio and video, QuickTime player is able to render the audio.


So without the packet number we need to do parsing;
Every Audio Frame Beginning is marked by the Marker bit as Zero;otherwise it will be 1 or TRUE;
If I developed the amr parser for this scenario, It causes the Screech Sound in audio with particular interval.At client side, I received the RTP packets and Dumped it into a file also givesthe same problem;

Solution:
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Finally I got the Solution:
we are sending video data at 5000 Port We are sending audio data at 5001 Port ;So it causes the problem;
Instead of it If I changed the things as
video as 4500 and Audio as 5000 means there will be no problem So Every RTP amr packet is having header Info;
For Audio and video There must be some difference.So that we can avoid this situation;

1 comment:

Nitin Goyal said...

Hey Man. Its extremely nice. I have lloking for such thing for long.

Actually, what I have is that I have a pcap having the RTP payload as AMR content. Now, I have to extract the RTP payload and decde the content using the ffmpeg and get the raw data and further encode that raw data into the mp3 or some other format. You have mentioned the AMR parser app, from whre i can get this app and do it work as i have mentioned. Thanks
Nitin