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Low Pass/Compression on broadcasts

Wasn’t sure where to post this or what tags to use but I have a question.

Recently have started a live streaming website and viewers/broadcasters have mentioned that the quality isn’t as good as other sites. Acting upon this, I investigated some competitors and analyzed spectrally our environment.

I have found that there is a low pass filter around 15kHz on the audio that is being presented to the broadcast. I have a developer going through the configuration now - but wasn’t sure if this was something that has already been solved or something that is known at all.

My analyses of some audio files:


  1. Each file was brought into a 48khz/24 bit pro tools session.
  2. A representative section was chosen from each clip then time aligned to allow for smooth switching between files.
  3. Each clip was measured with Insight2 to attain clip loudness and then normalized to the loudest clip. This value is -13.3 LUFS.
  4. A 128k mp3 was created from the original track as an extra data point.
  5. Each clip was rendered as a 48khz/24 bit file as Track_original and Tracks A-D.


Original track loudness: -13.3 LUFS | 2.8 LRA | -1.5dB TP

Volume live loudness: -17.9 LUFS| 2.8 LRA | -6.3dB TP, gain added: 4.6dB

Volume replay loudness: -13.5 LUFS | 2.8 LRA | -1.5dB TP, gain added: 0.2dB

Twitch live loudness: -19.3 LUFS | 2.8 LRA | -7.6dB TP, gain added: 6dB

Volume live frequency analysis

High cut filter at about 15.8khz, likely artifact of data compression. Also see the noise past the high cut.

Other streaming sites and the source do not have this high cut. I would provide more screenshots and analyses but my account is only able to send one screenshot since it is new.

Any help would be great!

Fig 1: Original track frequency analysis

This is the control file to which other files will be compared.

Fig 4: Twitch live frequency analysis

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