[FFmpeg-user] Why is concat so slow on a powerful machine?

Kevin Duffey kevinmduffey at yahoo.com
Thu Oct 26 00:08:28 EEST 2017


 Hey.. sorry if this top posts again.. I am not sure what that means exactly.. I am guessing it means this response shows up on top of other responses instead of the bottom. I am using email to reply though.. is there some way via email I can make it not top post? Or.. do I have to use some other web site to send posts? 
As for ffmpeg... just redid my system clean, everything running on NVMe in raid 0 (not that it will make much difference). I still can not understand what is causing it to go so slow. DNxHR SQ, 2 files, same as before, I cant get past 9fps. For not decoding/encoding, it is going WAY slower than Resolve does when encoding with FX. I can get about 30fps that way.  I would think that this should be hitting 100+fps or more. 
Is there some other issue anyone may know of that limits the speed at which ffmpeg runs? I mean its using < 1% CPU. That seems odd to me too. Is there something I need to do to tell it to use more cpu? I even tried opening a CMD prompt with admin rights.. hoping that may be it. 
Frustrated because this should be much much faster and is now causing my process to take 10+ hours for a 1 hour video. 
    On Saturday, October 21, 2017, 11:53:32 AM PDT, Tim Hiles <timothyhiles at gmail.com> wrote:  
 
 On Oct 17, 2017 6:22 PM, "Kevin Duffey" <
kevinmduffey-at-yahoo.com at ffmpeg.org> wrote:

Yup. I do not specify the output. I just use the same .mov file extension
as the two source files. Is it possible even though I specify -c copy
out.mov it is rendering and not Concat??
The pisser of this is that it is much faster putting the clips together and
rendering it out in resolve 14. I was hoping this would be much faster
since it is just concatting. But currently it is taking 10x longer.  That
can't be right. Even if it were rendering that is extremely slow.


2 things:

1. Send full command line and uncut complete ffmpeg output for users to
help evaluate your issue.

2. Do not top post to this email list.
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