lomiri-thumbnailer-admin(1)

💖 lomiri-thumbnailer-admin — Thumbnailer administrative tool 💖

okay bestie, sit down, hydrate, because we are reading the manual page for lomiri-thumbnailer-admin(1) from the Linux User's Manual, and it is lowkey the master key to the whole thumbnailer kingdom. let's get into it. ✨

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✨ SYNOPSIS ✨

lomiri-thumbnailer-admin command [options]

🌸 DESCRIPTION 🌸

So lomiri-thumbnailer-admin is your little admin bestie that talks directly to thumbnailer-service(1). What's it for? Retrieving a thumbnail, displaying statistics, or selectively clearing one or more of the service's internal caches. that's the whole job description, and it ate. 💅

🗂️ Internal caches

The thumbnailer service keeps three internal caches, and every single one of them has main character energy:

• Image cache — this one stores images that are expensive to retrieve, namely images downloaded from the image server (dash.ubuntu.com) or extracted from video files. Everything in here is kept at high resolution, up to a limit of max-thumbnail-size (usually 1920) pixels in the larger dimension (go peep thumbnailer-settings(5)). The image cache is what gets used to create thumbnails at smaller sizes, which then get inserted into the thumbnail cache — so we never have to repeatedly download or extract the original images. obsessed.
• Thumbnail cache — stores images that are scaled to a size a client previously requested. If a client asks for a thumbnail that was previously generated at the same size, it comes straight back out of this cache. no re-rendering, we're efficient here. 🦋
• Failure cache — contains the keys for media (local or remote) for which no thumbnail could be generated, either because a local file does not contain artwork, or because the image server has returned an authoritative answer that no image is available. If a client asks for an image that's sitting in the failure cache, the service does not try to create a thumbnail for some period of time — because expensive repeated attempts to retrieve artwork that does not exist is a flop and we don't do that.

Commands that can selectively be applied to these caches use the following cache-id:

• i — Image cache
• t — Thumbnail cache
• f — Failure cache

📐 Sizes and scaling

Thumbnails are never larger than max-thumbnail-size in the larger dimension (usually 1920, see thumbnailer-settings(5)), even if a larger size is requested. the limit is the limit, babes.

Commands that create thumbnails expect a size in pixels to be specified like this:

• widthxheight — Create a thumbnail scaled to fit a bounding box of width and height, for example --size 640x480. If only a single dimension is provided, the thumbnail is scaled to fit into a square bounding box of the specified size, for example -s 256.

Specifying a size with one dimension explicitly set to zero leaves that dimension unconstrained. For example, --size 0x480 produces a thumbnail no taller than 480 pixels of any width (subject to the max-thumbnail-size limit).

Specifying a size of zero (or not specifying any size) is equivalent to specifying max-thumbnail-size in both dimensions.

Scaling always maintains the aspect ratio of the original image, and ensures that a thumbnail has a size of at least one pixel in the smaller dimension.

Requests for thumbnails that are larger than the original image are automatically reduced to the original image size — that is, original artwork is never scaled up. no upscaling in this house. 🙅‍♀️

🖼️ Media formats and output files

Most common image formats are recognized, like PNG, JPEG, BMP, and so on. For streaming media, the recognized formats depend on the gstreamer codecs you have installed.

Thumbnails are always returned in PNG format, regardless of the encoding of the original image. And the generated thumbnail file is tagged with the requested (not actual) image size. For example:

lomiri-thumbnailer-admin get --size=320x240 screen.jpg

creates a file named screen_320x480.png. (yes bestie, read it again, that is literally what it says 💀)

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👑 COMMAND OVERVIEW 👑

Here's the whole menu, no gatekeeping:

• lomiri-thumbnailer-admin clear [cache-id] — Clear all internal caches.
• lomiri-thumbnailer-admin stats [cache-id] — Display cache statistics.
• lomiri-thumbnailer-admin zero-stats [cache-id] — Zero statistics counters.
• lomiri-thumbnailer-admin get file [dir] — Get a thumbnail from a file.
• lomiri-thumbnailer-admin get-artist artist album [dir] — Get an artist thumbnail from the image server.
• lomiri-thumbnailer-admin get-album artist album [dir] — Get an album thumbnail from the image server.
• lomiri-thumbnailer-admin compact — Compact internal caches.
• lomiri-thumbnailer-admin shutdown — Shut down the thumbnailer service.

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📖 COMMAND REFERENCE 📖

• lomiri-thumbnailer-admin --help, lomiri-thumbnailer-admin -h — Display a general help message for all commands.

🧹 lomiri-thumbnailer-admin clear [cache-id]

Options:

• --help, -h — Show help message.

Clear all three internal caches. If cache-id is provided, clear only the selected cache.

📊 lomiri-thumbnailer-admin stats [cache-id]

Options:

• --help, -h — Show help message.
• --verbose, -v — Show histogram of entry sizes.

Display detailed cache statistics. If cache-id is provided, limit the display to the selected cache.

🔢 lomiri-thumbnailer-admin zero-stats [cache-id]

Options:

• --help, -h — Show help message.

Reset the statistics counters and timestamps to zero. If cache-id is provided, reset the statistics only for the selected cache.

📸 lomiri-thumbnailer-admin get file [dir]

Options:

• --help, -h — Show help message.
• --size pixels, --s pixels — Set the thumbnail size.

Extract a thumbnail from the specified media file.

If dir is specified, place the thumbnail into the specified directory (default: current directory).

The output file name is basename_size.png. For example, for a file song.mp3, the output file name is song_0x0.png if no specific size was provided.

🎤 lomiri-thumbnailer-admin get-artist artist album [dir]

Options:

• --help, -h — Show help message.
• --size pixels, --s pixels — Set the thumbnail size.

Retrieve artist artwork for the specified artist and album. The album can be an empty string, but because artist names alone can be ambiguous, specifying an album as well may yield a better result.

If dir is specified, place the thumbnail into the specified directory (default: current directory).

The output file name is artist_album_artist_size.png. For example, for Jethro Tull's "Aqualung", the file name is Jethro Tull_Aqualung_artist_0x0.png if no specific size was provided.

💿 lomiri-thumbnailer-admin get-album artist album [dir]

Options:

• --help, -h — Show help message.
• --size pixels, --s pixels — Set the thumbnail size.

Retrieve album cover artwork for the specified artist and album. The artist can be an empty string, but because album titles alone can be ambiguous, specifying an artist as well may yield a better result.

If dir is specified, place the thumbnail into the specified directory (default: current directory).

The output file name is artist_album_album_size.png. For example, for Jethro Tull's "Aqualung", the file name is Jethro Tull_Aqualung_album_0x0.png if no specific size was provided.

🗜️ lomiri-thumbnailer-admin compact [cache-id]

Options:

• --help, -h — Show help message.

Compact all three internal caches so they take up the smallest possible amount of disk space. If cache-id is provided, clear only the selected cache.

After some time of use, the on-disk size of a cache can be 25–30% larger than its nominal size. Compaction reclaims the wasted space, but it is slow and, while it is in progress, other thumbnail requests are delayed until compaction completes. (It can take tens of seconds to compact a cache with a nominal size of 100 MB, depending on the speed of the hardware.) so like, plan around it, bestie. ⏳

🛑 lomiri-thumbnailer-admin shutdown

Options:

• --help, -h — Show help message.

Shut down the thumbnailer service. This is useful mainly after changing settings (which are read only once when the service starts). iykyk.

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🔗 SEE ALSO 🔗

thumbnailer-service(1), thumbnailer-settings(5)

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and that's the whole page, bestie!! this one came from Ubuntu, dated 05 August 2015, and it's filed under lomiri-thumbnailer-admin(1) in the Linux User's Manual. go forth and thumbnail responsibly. 💜 🎀 🫶