ffprobe reading hundreds of MB from remote NZBDav library during scan — can probe size be limited?

[gene0915 42]

I was messing around with InfiniDysk (a fork of NZBDav) and added a library full of symlinks to Emby through an rclone VFS mount.

The library path Emby sees is:

/mnt/md0/NZBDav/...

rclone is using VFS cache mode full with:

--vfs-read-chunk-size=16M
--vfs-read-chunk-size-limit=512M
--vfs-read-ahead=512M
--buffer-size=0M

During Emby's initial library scan, the server log shows ffprobe being launched like this:

/opt/emby-server/bin/ffprobe -i file:"/mnt/md0/NZBDav/TV Shows/..." -threads 0 -v info -print_format json -show_streams -show_chapters -show_format -show_data

I don't see an explicit -probesize or -analyzeduration being passed.

Most files probe very quickly, usually around 0.3–0.6 seconds. However, while watching the underlying NZBDav/rclone activity, I found some ffprobe reads going far beyond the initial 16 MB VFS chunk.

For example, one approximately 3.0 GB episode had already reached roughly 767 MB read while the Emby library scan was still running. There were also around 25 simultaneous active reads at that point.

rclone core/stats during the scan showed multiple 3+ GB media files open at once. Some were only at 688 KB or 8–17 MB, but others continued reading much farther into the files.

My concern is that on an NZBDav/Usenet-backed filesystem, a metadata scan that reads hundreds of MB from occasional files is very expensive and can trigger unnecessary article retrieval/cache activity.

My questions are:

• Is there an officially supported way in Emby to set a maximum ffprobe -probesize for library scans?
• Can this be applied only to regular media-library files, rather than Live TV?
• Is there also a recommended -analyzeduration limit for this situation?
• If there is no GUI setting, is there a supported configuration file or command-line option for supplying additional ffprobe arguments?
• Would limiting probe size to around 10000000 bytes cause any known issues with normal MKV media detection?

I would prefer not to replace or modify /opt/emby-server/bin/ffprobe directly because package updates could overwrite it, and I also don't want to unintentionally affect HDHomeRun/Tunarr Live TV probing.

Ideally I would like something equivalent to:

-probesize 10000000

applied only when probing files under:

/mnt/md0/NZBDav/

while leaving Live TV and other ffprobe usage at Emby's defaults.

If there is a supported way to accomplish that, I'd appreciate any guidance.

[Luke 42870]

HI, the question would also be about the impact on server transcoding, because it relies on this information to be accurate. And to be honest, not just transcoding but all of playback. Even direct playing looks at this information heavily.

[gene0915 42]

5 minutes ago, Luke said:

HI, the question would also be about the impact on server transcoding, because it relies on this information to be accurate. And to be honest, not just transcoding but all of playback. Even direct playing looks at this information heavily.

Thanks for the reply! Probably a really crazy question but, would it be possible to have Emby see that a file is a symlink and have a hard-coded limit as to how much of the file it reads to satisfy ffprobe?

It seemed that most of the episodes, it flew through them and only needed to read 5-15 megs of data but every now and then, it would encounter a file that it wanted InfiniDysk to download all of it.

Do you think this would be a problem if I were using strm files?