Thanks for measuring Bouke! Guess momentary isnt working with <0,4s too.
I tried my example with adding silence before and after and i get both times -23.3db LUFS for i & m. Which is a 1db variation to the customers value. If all files are coming with a 1db difference, that would be something we could work with. So we are not precisely here, but its good enough for now. I wonder how the meters are measuring it. As they dont have problmes with durations. We will try ... -----Ursprüngliche Nachricht----- Von: ffmpeg-user <[email protected]> Im Auftrag von Bouke Gesendet: Montag, 14. September 2020 14:08 An: FFmpeg user questions <[email protected]> Betreff: Re: [FFmpeg-user] LUFS measurment for short length audio > On 14 Sep 2020, at 13:54, <[email protected]> > <[email protected]> wrote: > > Its all mono we are talking about here > > Full command line would be > ffmpeg -nostats -i '#{filename}' -filter_complex ebur128 -f null - > 2>&1 (i only forward this from the IT section, but its the standard > ffmpeg lufs measurment as far as i know) > > yes, we dont know if the customer values are correct. The problem is, there > is no correct if you dont use the same method/algo. > There are different meters coming up with different values on LUFSs, > specially if you are under 0,4s. > You are right, the best would be to use the same method, but our customer > wont share their method and we cant reverse engineer something we dont own. > > Yes, there ist the (m) value in the output, but i think its not very > reliable ... as the file measured isnt silent 😊 I would think M is not relevant, as it should equal I if the file is 400 Msecs… And I can reproduce the issue on a short file. But, if I cat the file with silence before / after, then measure with adding -ss yadda -t sourcedur it seems to work. (But a looped input results the same values when scanned fully.) Bouke. > > > > -----Ursprüngliche Nachricht----- > Von: ffmpeg-user <[email protected]> Im Auftrag von Bouke > Gesendet: Montag, 14. September 2020 13:41 > An: FFmpeg user questions <[email protected]> > Betreff: Re: [FFmpeg-user] LUFS measurment for short length audio > > >> On 14 Sep 2020, at 13:23, [email protected] wrote: >> >> >> To cat means to loop the file until it is longer then 0,4s? > > yes > >> >> Yes we tried, there is a variation of 3db or more, so it is kind of >> suboptimal. > > If it’s exact 3db, it smells like you might render the file to mono on > catting, are you sure that’s not the case? > >> We also know the loudnorm command. > > Why, if you want to conform to R128 specs, you analyse, get the I > value, and lower / up the volume by the measured Integrated minus > target Integrated (in Db, one LU is equal to one dB) >> >> We use this command atm to read out values: >> >> ffmpeg -nostats -i 'filename' -filter_complex ebur128 -f null > > This might or might not work, if it’s 5.1, you would need to omit the LFE > channel, and if there are multiple tracks you would need to patch the correct > ones first. > So, full command line / output missing :-) (I would never think I > would write this…) > >> and it is fine with all files >0,4s. As it should be relating to the ebu128 >> definition. >> >> Anyway, our customer provides us with lufs values for shorter lenghts and he >> wont tell us how he analyses it. > > So you have no clue if your client measurements are correct? I would not > accept this, you would need to reverse engineer your clients steps... > >> >> Now we tried to read out momentary lufs, as it works with 400ms windows, but >> im not sure if i get correct values here. >> As it shows -120db mLUFS for an example and on proTools it says >> -23--24db (with DPMeterXP2) > > -120 is silence… > >> >> Anybody an idea how to read out reliable momentary LUFS values with ffmpeg? > > Not sure how reliable it is, but it’s just in the output I would > think… > > Bouke > > >> >> -----Ursprüngliche Nachricht----- >> Von: ffmpeg-user <[email protected]> Im Auftrag von Gyan >> Doshi >> Gesendet: Montag, 14. September 2020 09:50 >> An: [email protected] >> Betreff: Re: [FFmpeg-user] LUFS measurment for short length audio >> >> >> >> On 14-09-2020 01:15 pm, Bouke wrote: >>>> On 09 Sep 2020, at 10:33, [email protected] wrote: >>>> >>>> >>>> >>>> Hi list! >>>> >>>> >>>> >>>> Can somebody help to measure LUFS for audio files under 0,4 seconds??? >>>> >>> Cat it a couple of times first? >> >> A few more times is required. Total duration should be >3 seconds. >> >> See https://superuser.com/q/1281327/ >> >> Gyan >> _______________________________________________ >> > > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email [email protected] > with subject "unsubscribe". > > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
