[FFmpeg-devel] One pass volume normalization (ebur128)

Jan Ehrhardt phpdev at ehrhardt.nl
Wed Jul 17 11:12:04 CEST 2013

Reimar Döffinger in gmane.comp.video.ffmpeg.devel (Tue, 16 Jul 2013
21:30:04 +0200):
>> Execution time: 16.765 seconds.

>> Execution time: 27.154 seconds
>> Please tell me where I go wrong. And/or guide me to a quicker
>> volumedetect an a concatenated audio track.
>You probably have write caching or something similar off
>(on Windows, it is off by default for anything it believes
>you might be able to detach).

Yes, I know caching is off but I cannot control that on the user-PC's.
I've already searched for methods to change it programmatically, but
could find no way.

>If you use log/temporary files you really should be
>using a disk suitable for it.

I cannot even use the HDD of the PC. In between the SD card and the PC
are all kinds of IT-obstacles and privacy-related issues.

>Since pipes are unfortunately a rather unusable pain,

Actually, that was not that hard. Adding 2>&1 | find "mean_volume" to
the commandline gave me the desired line. However, due to the lack of
grep and sed on Windows it is not easy to parse that line further. If I
would need to, I'd probably use the PHP on the SD card to parse it

>a RAM disk would be the best performing alternative.

I have been on that track as well, but for another reason. Space is
limited on the SD cards. Sometimes there is not enough room for the
output file. My largest output file has been 1GB (5:28h 400*300 MP4) up
until now. A 1GB+ ramdisk would be ideal in those cases. If you know a
commandline installable RAMdisk with no need for registry access...


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