Icecast True peak troubling values

[JeanXeb]

Hi Radioboss,

I detected different values between the studio output, then the encoding and reading of significant true peak.
Studio output : - 1.5 dB True Peak (protection)
Reception in the audio player : +2.7 dB True Peak (Reliable value)

The rise in value seems to be changed at the time of Icecast encoding.

It is impossible to take control of True Peak despite audio processing with -1.5 db TP protection. (Even more)

For FM / DAB broadcasters this generates heavy disturbances (collect).

Would it be possible to fix this problem ?

Cordialy

 

[HMMMM]

Paulo what sound controls are you using are you using track gain or are you using perhaps a track gain on al mp3 as well as the general setting gain. There are lots of ways to gain your signal. You didn't say if you were using DSP or stereo Tool to broadcast FM / DAB

 

[JeanXeb]

Can someone from the radioboss staff answer me ?

 

[djsoft]

The rise in value seems to be changed at the time of Icecast encoding.

Encoding in RadioBOSS doesn't change sound level. However, encoding is not affected by the volume slider that is located under the playlist (encoding is performed at 100% volume level). Maybe this is the case?

 

[JeanXeb]

Thank you for your reply !
It's a machine without a sound card.
If you do the test you will see that until the encoding everything is perfect !
Then, you retrieve the stream in a neutral player with an analyzer inside and there the values are irregular. (dB TP)

 

[djsoft]

It's a machine without a sound card.
If you do the test you will see that until the encoding everything is perfect !

If there's no sound card, how do you check it without encoding? Also, you can try using a different encoding format and bitrate - maybe sound issues are introduced by the encoder?

 

[JeanXeb]

I do the encoding from the machine without a sound card.
I retrieve the icecast2 audio stream in a player (neutral) on another machine which allows me to do the measurements.
It was our FM/DAB broadcaster who challenged me on this problem which is causing major problems in their infrastructure.
The problem is present in mp3 and aac+ encoding

 

[djsoft]

I retrieve the icecast2 audio stream in a player (neutral) on another machine which allows me to do the measurements.

You can check the stream before it's encoded for streaming if you activate "Stream Archive" function in RadioBOSS.
But from technical point of view - Icecast does not modify audio data, there's no code that will do it, so whatever's broadcasted, listeners will get with no modification.
From RadioBOSS side, audio stream that goes to streaming servers, is exactly the same stream that will go to sound cards. With few exceptions: it will not take into account "Volume" slider under the playlist, and there's some special processing for MIC if you have "Output to encoders only" option enabled in Input settings. Apart from that, audio is not modified for streaming.
So, I suppose the problem here is caused before audio is encoded, e.g. some plugin in RadioBOSS or audio tracks themselves have issues etc.

 

[HMMMM]

Um Dimitri yes but please don't forget some streams are different bitrates it depends on stream we are all used to 192kbs but many around are 128kbs still and will not sound the same as RB which will I presume run at highest it can.