[FFmpeg-devel] EBU R128 Filter Mono vs Stereo results

[Paul Figgiani]

In a generic example If I analyze a stereo file using the EBU R128 filter and it returns -16.0 LUFS as the Integrated (Program) loudness ... and then play the example file in a DAW and pass it through a compliant Loudness Meter - the results are consistent.
In a second generic example If I analyze a mono file using the EBU R128 filter and it returns -19.0 LUFS as the Integrated Loudness ... and then play this example file in a DAW and pass through a loudness meter - the Loudness Meter displays -16.0 LUFS. The results are off by 3 LU.
Can someone elaborate?
Thanks.