High CPU usage when audio transcoding?

[TheDreadPirate]

On an 8100T, I'm not surprised with that level of utilization. Four old, low TDP cores.

The audio is probably pegging one core while other ffmpeg tasks (demuxing, remuxing, moving data around, etc). are on several other threads.

I used to run Jellyfin on an Intel J4205 and audio transcoding, no video transcoding, used quite a bit of CPU power.

[SVRUM]

On an 8100T, I'm not surprised with that level of utilization.  Four old, low TDP cores.

The audio is probably pegging one core while other ffmpeg tasks (demuxing, remuxing, moving data around, etc). are on several other threads.

I used to run Jellyfin on an Intel J4205 and audio transcoding, no video transcoding, used quite a bit of CPU power.

So this is just a normal amount of CPU usage then? Would a higher clocked CPU or more cores be the thing to look for? I was just surprised when I was looking for machines to build out I didn’t thing transcoding audio would be that big of a resource hog. I guess I could also just edit the audio files in the file itself

[TheDreadPirate]

Keep in mind that ffmpeg will transcode as fast as possible. High utilization is fine as long as it is transcoding at a really high frame rate. In your case it is going at about ~350-400fps when just transcoding audio. Your setup could handle many more simultaneous audio transcodes before CPU performance became a problem. Assuming just audio transcoding, it could probably handle ~10 more simultaneous streams comfortably.

Pre-transcoding is an option, but it is a lot of work if you don't have consistently have 10+ users. If it is only you and 1-2 friends, your setup is perfectly capable of handling the load. Even video transcoding.

[SVRUM]

Keep in mind that ffmpeg will transcode as fast as possible.  High utilization is fine as long as it is transcoding at a really high frame rate.  In your case it is going at about ~350-400fps when just transcoding audio.  Your setup could handle many more simultaneous audio transcodes before CPU performance became a problem.  Assuming just audio transcoding, it could probably handle ~10 more simultaneous streams comfortably.

Pre-transcoding is an option, but it is a lot of work if you don't have consistently have 10+ users.  If it is only you and 1-2 friends, your setup is perfectly capable of handling the load.  Even video transcoding.

Hmm okay, so was just surprised that it was that high. You mention transcoding audio at 350-400fps, how does that work? Is that number in the logs? Could you for example for e it to transcode at a slower frame rate, I’m assuming it’s matching to the frame rate of the video, 24fps in this case right? Lower CPU usage that way?  I’m new to the whole video transcoding stuff, I only know different formats for music CD’s and things.

[TheDreadPirate]

Normally it prints in the ffmpeg the frame rate it is transcoding it. Sometimes it doesn't (I don't know why). But it was printing the multiple above real time it was transcoding. So it was a 24FPS video and it was transcoding up to 17x faster than real time. So 24x17.

There is no way to have ffmpeg only transcode at 24fps. Nor do you want to. You always want it to build up a buffer. What you can do is tell ffmpeg to pause once it gets far enough ahead.

Dashboard > Playback > Transcoding

Near the bottom is a setting "throttle transcoding". The default, IIRC, is to pause once it is 5 minutes ahead of the current position in the video. After a minute or two it will start transcoding again to build the buffer back up to 5 minutes.