9 Aug
2014
9 Aug
'14
8:06 a.m.
There are two ways to slow down the sound with a factor 25/24: change
the tempo or change the speed.
Change the tempo will try to keep the pitch but need a complex algorithm
to do it with good results (the best one is dirac, available with time
factory). Change the speed will change the pitch and the tonality of the
voices and music. Not really suitable in terms of production and clearly
audible. But it is the solution that is used in many labs.
ffmpeg has a very bad algorithm (atempo) to change the tempo and I did
not find a way to change the audio speed.
You can use sox with the speed option.
I don't know how is doing dcpomatic, so I change the speed of the sound
before with sox, and the speed of the video with ffmpeg to provide
dcpomatic a 24 fps source.
Lilian
Le 09/08/2014 00:39, Carsten Kurz a écrit :
Am 08.08.2014 um 23:29 schrieb Ben Edwards:
Hi, I just discovered the source material is
25fps, was planing on making a 24fps DCP I beleve some ceinmas do not support 25? is
this correct or should I create a 25ftp DCP.
How good is DCPOMsatic at doing frame rate conversion? I am sure it is great but thought
it better to ask.
Ben, you're learning it the hard way - formally, 25fps is not
supported in Interop DCPs. It may work on some systems, but I have no idea how often it
will fail.
Dolbys DSS100/DSP100 does not support 25fps with DCP content, not in Interop, not in
SMPTE format.
Most digital labs/companies slow down 25fps features to 24fps, as Carl explains. If you
choose 24fps DCP with 25fps content, dcp-o-matic does all the necessary steps for you.
- Carsten
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