[Question] Speed up process? about sickbeard_mp4_automator HOT 2 CLOSED

This is more of a general FFMPEG question and maybe not the appropriate place to be asking but I can give some general guidance

Without logs it will be hard to nail down a specific bottleneck but there's always going to be some kind of bottle neck

If you're remuxing everything and doing no transcoding then your HDD (or SSD) read/write speeds will be your main bottle neck

Metadata writing for MKVs does do a second pass and essentially writes the metadata with a full remux transcode as a second step so this can add some time since it essentially has to rewrap the streams in a fresh mkv container, but this is only limited by your drive read/write so should be relatively quick still, mp4's don't have this limitation since they are written by mutagen (though mp4s usually get processed by qtfaststart which also needs to rewrap the file so you come out even)

Transcoding is always where you lose the most speed

Video being the slowest even with hardware transcoding
Software video transcoding depending on hardware can take hours
Certain filters aren't supported by hardware transcoding so even when using hardware you can have a software layer that slows it down substantially

Then audio
FFMPEG audio transcoders are pretty much all single threaded and do not benefit from hardware acceleration so it can take some time for larger sources but still should be measured in minutes not hours, an order of magnitude faster than video

Then subtitles which is almost negligible since its only text based subtitles which takes a few seconds at most

The other thing to consider is source material; Content length/duration and bitrate play a huge role. Higher bitrate means more data. This makes every part of the process take longer. Remuxing will take longer just due to bigger size. Transcoding can take longer for more complicated formats (more audio channels, higher fidelity formats, higher bitrate all make audio transcoding more complicated and time consuming). And higher quality transcoding comes at the cost of time.

You can watch the SMA logs to see if there's a particular spot that things are hanging but the times you are reporting don't seem excessive

I also use a ramdisk for most of my transcoding which speeds things up but you need quite a bit of ram for this approach, but this won't be huge gains over an ssd

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OK makes sense then. Thanks!

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