Choppy audio and bad audio quality when recording to the KMS Server

[natas12...@gmail.com]

Hi,

We have been testing Kurento Media Server and we are having some issues; the most important is related with audio recording:

First, we installed the last stable version and we tried the kurento-recorder-screen and kurento-recorder demos; audio&video were succesfully saved on the server (in a webm file) but the audio was recorded with PCM MuLaw, whose quality is poor. 

Then we installed the development version and we got Kurento recording using the Vobis codec, with a samplerate of 48.000 (stereo). That should be a good audio quality, but when we record audio&video (using a proffesional microphone), the audio is choppy (the voice looses and comes back) and the voice sounds like robotic (just like a telephone quality)

Any ideas of what is happening and how can we solve this? 

Also, in the development version, we were unable to run the "one-to-one" demo; I guess we succesfully tested on the stable version, but now, we are receiving the following error:

debug KurentoWebSocketTransport WebSocketTransport.cpp:480 processMessage() Response: >{"error":{"code":40004,"data":{"type":"CONNECT_ERROR"},"message":"Media elements does not share pipeline"},"id":4,"jsonrpc":"2.0"}

Is this because the development version?

Many thanks in advance!

Best regards,

Alejandro

[natas12...@gmail.com]

Hi again,

After investigating, we finally discovered the reason of bad audio quality while recording: it is because the examples kurento-recorder and kurento-recorder-screen use "startSendRecv" Method, that sends video/audio and receive them again. That seems to cause some kind of issue, because after editing that line (using startSendOnly) the problem was solved. Now the audio is fine!

So, it seems to be some kind of bug with the sartSendRcv method?

The other issue, the problem with the "one2one" demo, is still not working... we don't know if the demo is outdated or if we are mistaking something...

Regards,

Alex

[Ivan Gracia]

Hi Alex,

Sorry for the delay, and thanks for all the efforts you've put into finding the source of the problem. Maybe by setting the RTCPeerConnection in send-recv mode, there are some glitches in the audio. We hadn´t tested this with high-quality microphones, so we didn´t experience this before, so it's really good to know.

As for the issue with the tutorial, I´ve just checked kurento-tutorial-java/kurento-one2one-call and is working fine. Which flavour of the tutorials are you using?

Ivan Gracia

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[natas12...@gmail.com]

Hi Ivan,

Thanks for your reply! We finally solve the problem, it seems we were using a bad demo, because it wasn't based on nodejs, just JavaScript. We installed the official demo and now works fine.

Now we are facing another challenge:

When we record video/audio with the kurento-recorder-screen in WEBM format, we get stereo audio with vorbis códec (very good quality) and video with normal quality (V8 códec);

When recording in MP4 format, we get better video quality (using H264 códec) but worse audio quality (MPEG códec with MONO channel)

We are desperate looking the way to record in STEREO and MP4... and to be able to change video/audio quality parameters (framerate, bitrate, etc)... we have beein investigating GStreamer filters but we do not know how to use them, even if we can use them for this.

What are the ways to change these parameters? How can we record in STEREO when using MP4 mediatype? How Gstreamer filters are used?

NOTE: We develop in JavaScript, so we are interested in using the JavaScript API.

Many thanks in advance... y que pases un buen día :-)

Saludos!

Alex

[Ivan Gracia]

Well, mp4 is not thoroughly tested. We are focusing our efforts in webm right now. Also, quality and stereo depend on you using opus in your webrtc.

Ivan Gracia