macOS Video Conversion Script

Overview

This script converts videos to HEVC (MP4), followed by an MKV Annex-B remux, while preserving selected audio and subtitle tracks.

It leverages Apple’s hardware-accelerated encoder hevc_videotoolbox and lets you customize resolution, bit depth, frame rate, audio formats, subtitles, and languages.

All processed files are saved in a user-defined output directory.

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Installation

1. Save the script, for example as convert_videos.sh.
2. Make it executable:

   chmod +x convert_videos.sh

3. Place your source videos in a folder, e.g. ./input.

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Running the Script

bash convert_videos.sh

The script will walk you through each setting step by step.

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Options Overview

Option	Description	Default	Example
Resolution	Target video resolution	1080p	1=1080p, 2=4K
Input Folder	Folder containing source videos	./input	./my_videos
Output Folder	Folder for converted videos	./output	./converted
Framerate (FPS)	Target frame rate. Leave blank to keep original	Original	30
Bit Depth	Video color depth	8bit	10bit
Quality (Q)	HEVC Videotoolbox quality factor (lower = better quality)	65	50
Languages (Audio & Subtitles)	Language filter for tracks (comma-separated)	ger	ger,eng
Audio Format(s)	Audio format conversion/passthrough (comma-separated)	ac3	aac,ac3,eac3

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How It Works

1. MKV Creation

• The video is encoded to MKV using hevc_videotoolbox.
• Audio tracks are either passed through or converted based on your settings.
• Missing tracks are automatically generated if needed.

2. MKV Annex-B Remux

• Combines the encoded MP4 video with audio and subtitles from the original file.
• Subtitles in selected languages are preserved, including default and forced flags.
• Applies the HEVC Annex-B filter for maximum compatibility.

3. Output

• All finished files are saved in the specified output directory.
• Filenames follow this pattern:

  <original_name>_HEVC.mkv
  

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Multiple Languages and Audio Formats

• Example for multiple languages:

  ger,eng,fre
  

• Example for multiple audio formats:

  aac,ac3,eac3
  

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Notes

• Only the audio formats aac, ac3, and eac3 are directly supported for passthrough.
• If you leave the Framerate blank, the script keeps the source frame rate.
• 10-bit HEVC videos are correctly encoded as 10-bit output.
• The script is optimized for macOS and Apple Silicon hardware acceleration.