Kieran Kunhya in gmane.comp.video.ffmpeg.devel (Sun, 14 Jul 2013 16:20:27 +0100):
R128 refers to programme loudness.
I believe you. But aren't there loudness recommendations for live steams of popconcerts, the Bayreuther Festspiele or the like?
As far as I know this is the job of the mixing engineer using traditional meters.
Strange, since there are methods to come close to the EBU recommendation for prerecorded programs.
I really think this patch should not be committed since it has little to do with R128, although a lot of commercial manufacturers call their realtime products R128 compatible.
OK, that is an argument I did not hear before. And the argument seems plausible. But am I remembering it correctly that you were the one that once on #ffmpeg-devel uttered the wish to do normalization on the fly? Did you change your mind?
I also don't understand why you specifically need 1-pass when you appear to have a file-based workflow.
Simple, speed. My users are professionals that record interviews with their clients (with their consent) and put them securely online to get feedback from their colleagues and coaches. The typical recording is one to two hours, depending on the project. But last week someone from Kansas even uploaded a 5:28h recording (1GB after transcoding to 400*300). The project in Kansas has put 7000 hours of video online since they started in October 2011, so they are doing a lot of transcoding. I try to squeeze out every minute of the transcoding time to keep my users satisfied. FFMpeg 2.0 was a happy surprise because it was about 10% faster than the previous version I had rolled out to the users. For volume normalization I have long been depending on the -af volnorm filter of MEncoder. But MEncoder is not maintained anymore, so we were looking for an alternative for '-af volnorm' within FFMpeg. Clement's patch provided us with that. I am in no way bound to EBU recommendations, so maybe we should rephrase the issue: how can we implement an equivalent to the -af volnorm filter in FFMpeg? See here for the docs on -af volnorm: http://www.mplayerhq.hu/DOCS/man/en/mplayer.1.html#AUDIO%20FILTERS Jan PS. http://x32.elijst.nl/single.mp4 is a good example why I need volume normalization. The video is too short to make full use of the filter. The volume is only increased from -40 LUFS to -35. But if I use the same video 4 times in a row the volume is already raised to -23.8 LUFS. So with videos of 40+ seconds I get the desired result.