[FFmpeg-user] Multiple outputs worse performance than multiple instances

[Jason Runta]

Can you post your ffmpeg commands? I am doing something similar and I'm not
seeing a significant CPU increase.


On Fri, Oct 11, 2013 at 9:33 AM, Carl Lindqvist <lulebo at gmail.com> wrote:

> Hello
>
> I am trying to optimize my encodings. I have a single input file and
> transcode it to multiple bitrates with FFmpeg using x264 as codec. At
> the moment I am starting one instance of FFmpeg for each output. This
> seemed wasteful, so when I learned of the "multiple outputs"
> (https://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs) in FFmpeg
> I wanted to try that. My results are very bad. Performance is much
> lower than starting multiple instances. I have tried putting -threads
> here and there in the command without getting good cpu usage.
>
> The problem is that cpu usage is hovering at 15-20% (machine has 12
> cores, 24 threads with hyperthreading). When I run multiple instances
> I get 98-100% utilization and much higher encode speeds.
>
> I would think running one input (and therefore one
> read/decode/deinterlace) should be much faster. Does anyone have any
> experience with this? Is it a bug or am I simply doing it wrong?
>
> Best regards
> Carl Lindqvist
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-- 
*-_-=Jason Runta=-_-*