optimize

The optimize command is the primary command. It finds all of the videos in a target directory, and re-encodes them into HEVC/h.265.

• While it’s processing a video, it will have an .optimizing tag (i.e. video.optimizing.mp4)
• After processing, the tag will change to .optimized (i.e. video.optimized.mp4)

If an outage occurs while optimizing, simply re-run the command against the same directory. When NanoEncoder encounters a file with .optimizing still in the name, it will delete the partially optimized file and re-encode the original.

After a directory is fully processed, you may run the health command to get a grade on how well it did, the purge command to remove the original video files, and the untag command to safely remove the .optimized tags from the file names.

Usage

One should experiment with a small sample of videos (like if you’re optimizing a season of a show), at varying crf values, and visually comparing the results. A feature will be released soon™ to aid with process.

# Re-encode with default settings (crf: 28, preset: medium, tune: None)
nen optimize "/media/series/Mob Psycho"

# Re-encode with default settings, but stop if any file size increases
nen optimize --halt-on-increase "/media/series/Mob Psycho"

# Re-encode with default settings, but downscale the resolution to 720p
nen optimize --downscale 720 "/media/series/Mob Psycho"

# Re-encode at CRF 18, "virtually lossless"
nen optimize --crf 18 "/media/series/Mob Psycho"

# Re-encode with "ultrafast" preset AND "animation" tuning profile
nen optimize --preset ultrafast --tune animation "/media/series/Mob Psycho"

# Force re-encode, regardless if video is already in h.265 or not.
nen optimize --preset ultrafast --tune animation "/media/series/Mob Psycho"

# Re-encode and immediately replace originals with optimized versions
nen optimize --replace --crf 25 "/media/series/Mob Psycho"

For shows

If you’re re-encoding a show, you should test your CRF setting on a small sample of videos for each season. If your show spans a decade, the same settings may offer varying results.

For movies

Sampling a portion of a movie isn’t practical. For movies, use 17-18 CRF, which is considered “visually lossless.”

--crf flag (default: 28)

Use the crf to adjust the tradeoff between detail preservation and file size. It can be anywhere from 0-51. The “best” value is subjective and varies between files.

Too low of CRF (<18) may actually INCREASE the size of your file! NanoEncoder will warn you of file increases.

Read the more at the about-crf.md page

--preset flag (default: medium)

FFmpeg offers presets to further control how much size is saved, but this time in relation to encoding times. NanoEncoder uses the same default FFmpeg does for this encoding type, medium. The documentation says “use the slowest preset you have patience”, as this will result in the smallest video sizes.

Available presets: ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, and veryslow.

--tune flag (default: None)

Finally, for even further control, one can specify a tuning profile. Check out the official documentation for more info, but the most commonly used tuning profiles are also the most self evident, grain and animation. grain is for older movies which tend to be grainer. animation is for cartoons, anime.

Available tuning profiles: animation, grain, stillimage, fastdecode, and zerolatency.

--downscale flag (default: None)

You can resize your videos to further decrease file sizes. This flag takes a width as input, and the height is determined by the aspect ratio of the video. Examples sizes are 720 & 1080.

--halt-on-increase flag (default: False)

Stop the a directory if any video’s output size is larger than its input size. This is useful as a size increases often means that the CRF value is too low for efficient compression.

--replace-after / --replace flag (default: False)

Automatically replace the original video files with their optimized versions after processing. This flag combines the functionality of the purge and untag commands into the optimization process.

When enabled, NanoEncoder will:

1. Optimize videos as usual with .optimized tags
2. After each video completes successfully, safely delete the original file (moved to trash/recycle bin)
3. Remove the .optimized tag from the optimized file, effectively replacing the original

This doesn’t allow you to have a chance to use health subcommand.

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Full help output:

usage: NanoEncoder optimize [-h] [--crf CRF] [--downscale DOWNSCALE]
                            [--preset {ultrafast,superfast,veryfast,faster,fast,medium,slow,slower,veryslow}]
                            [--tune {animation,grain,stillimage,fastdecode,zerolatency}]
                            [--force] [--halt-on-increase] [--replace-after]
                            directory

positional arguments:
  directory             Path to the target directory

options:
  -h, --help            show this help message and exit
  --crf CRF             Constant rate factor, between 0-51 (default 28))
  --downscale DOWNSCALE
                        Downscale video resolution to a specified height
                        (e.g., 1080 or 720). Maintains aspect ratio (default
                        None)
  --preset {ultrafast,superfast,veryfast,faster,fast,medium,slow,slower,veryslow}
                        Set the encoding speed/efficiency preset (default:
                        medium)
  --tune {animation,grain,stillimage,fastdecode,zerolatency}
                        Set the tuning profile (default: None)
  --force               Force encode even if video is already in h.265 format
  --halt-on-increase    Stop processing if any video's size increases after
                        optimization
  --replace-after, --replace
                        Replace the original video file with the optimized
                        version (delete original and remove '.optimized' tag)