Need help to play live stereo G711 audio by Wowza Streaming Engine
We are evaluating the Wowza Streaming Engine and consider using it in our product.
As first step, we are checking the Wowza ability to transcode G711 RTP audio packets to AAC and we try to play it by html 5 DASH player.
For the POC we are using:
Wowza Engine Version - 4.2.0 (build 15089), Engine Manager Version - 4.2.0 (build 15089).
License - Wowza Streaming Engine 4 Trial Edition
License Restrictions: Maximum Total Connections: 10 , Maximum Incoming Connections: 3 , HTTP Origin: Not available.
During the POC we encountered the following issues which we would like to get answers for.
1. Wowza does not open more than 2 RTP ports.
Our business is about playing phone calls. We would like to deliver G711 RTP packets on 2 different ports (stereo): one port for each side of the call.
According to SPD specifications, media streams are transmitted via pairs of RTP and RTCP ports. By default, there is only one pair of RTP and RTCP ports but we can configure the SDP for more than one channel and thus cause more pairs of RTP and RTCP to be opened.
For example, if we set the sdp file with the following media descriptor:
m=audio 9000/2 RTP/AVP 0
we would have expected Wowza to open 4 ports: ports 9000 and 9001 for one RTP/RTCP pair and ports 9002 and 9003 for the second RTP/RTCP pair.
However, we found (using netstat command) that the Wowza Streaming Engine always opens only 2 ports for audio no matter what we request in the media descriptor of the SDP file.
Do we experience this issue because of the trial version that we have? Is it something that Wowza actually not support? Or we simply miss something?
2. Live audio playback is scrambled and not clear.
We tried using the Wowza Test Players (Adobe RTMP, Abobe HDS) as well as our own DASH player and all players give the same bad audio quality results.
3. For confidential purposes, we would like to know if the Wowza Streaming Engine keeps its jitter buffer or any other audio cache buffer on disk? If the answer is yes, we would like to know whether there is an option to keep it on RAM?
1. Wowza Streaming Engine only supports a single audio track per stream and with rtp, it will select the first track it locates in the sdp file. There is an option with Mpeg-TS to specify which track to select but that option is not available with rtp.
2. It's difficult to tell what the problem is with the streams without examining them. If you would like us to check this then please make a debug recording of the rtp stream and submitting it in a support ticket. Please also include a link to this forum thread.