thumbnail extraction using only 1 thread

[xvv 2]

currently, the thumbnail extraction seems to be using only 1 thread:

emby version: 4.4.3.0 (emby/embyserver docker image)

/bin/ffmpeg -f mp4 -threads 1 -skip_interval 10 -copyts -i file:[removed] -an -sn -vf select='eq(pict_type,PICT_TYPE_I)' -s 320x173 -vsync cfr -r 0.1 -f image2 [removed]/img_%05d.jpg

it used -threads 0 in the past, not sure when/why this was changed.

(my test with standalone ffmpeg showed an fps increase of about 80% with 2 threads)

[Luke 42083]

@softworkz may have some insight.

[softworkz 5072]

On 6/12/2020 at 7:37 PM, xvv said:

(my test with standalone ffmpeg showed an fps increase of about 80% with 2 threads)

I'm don't know what you have tested, but I'm sure it was something different than what Emby does, because a normal ffmpeg does not have the skip_interval parameter. Our quick-extraction method cannot be accelerated with multiple threads.

Before complaining, please compare the performance of "your test" with emby's extraction. 

Thanks