Transcoding when audio track is in container already

[gregoliver]

Hi,

plexmediaserver-1.13.5.5291-6fa5e50a8.x86_64

I just noticed something(s) odd.

1. The Plex Transcoder is using more CPU to transcode 7.1 TrueHD to AAC than it uses to transcode h.264 to 3mb/sec. It is really odd - it spikes all 8 threads of my i7 to 100% for 6 seconds every 10 seconds. The machine transcodes h264 video with less resources.

2. The same mkv container already has an AAC tracm in it - why not just stream it direct?

Anyone know why? TiA!
-Greg

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  | + Codec ID: A_AC3
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  | + Default duration: 00:00:00.032000000 (31.250 frames/fields per second for a video track)
  | + Name: Surround 5.1
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  | + Sampling frequency: 48000
  | + Channels: 6
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[ChuckPa]

PMS looks at the default track.

Your media shows:

| + Track UID: 2
| + Track type: audio
| + Default track flag: 1
| + Lacing flag: 1
| + Codec ID: A_TRUEHD
| + Language: eng
| + Default duration: 00:00:00.000833333 (1200.000 frames/fields per second for a video track)
| + Name: Surround 7.1
| + Audio track
| + Sampling frequency: 48000
| + Channels: 8
| + Track
| + Track number: 3 (track ID for mkvmerge & mkvextract: 2)
| + Track UID: 3

This is the default track . It happens to be the most complex to decode. If your player (TV) can’t decode it natively, PMS will.

If you wish to change this behavior, you have two choices.

1. modify the default track in the file permanently.
2. select the AAC track in the pre-play screen.

[gregoliver]

Yep, I know I can do that - was just wondering. I was more concerned with the CPU usage. I just extracted the TrueHD track and converted it with my version of ffmpeg and it was the same result as I was seeing last night.

I have just never seen (or been looking) at how much it takes. Just not used to audio conversion being that heavy, but I guess it is what it is.

I zm currently running Plex on the same server as my MythTV backend since all of my Media is also on that server. Do you know if there is a way to split out the Plex Transcoder onto another machine? I am currently using cgroups to keep resources in check so my recordings are commflagged and all that without issue, but it sometimes causes Plex to require up to a minute to start playback if I am recording 5 or 6 things at once. If I could split the Transcoder out to a virtual machine on another server, I could alleviate the delay.

I do not see an obvious way to accomplish it though.

Thanks!