How to hardcode subtitles in a
MK3D video in 6 steps

The Difference Between Hardcoded and Soft Subtitles

When you hardcode subtitles into a MK3D video, you permanently embed the text directly into the video frames themselves. Unlike soft subtitles (also called closed captions), which are stored as separate text files that viewers can toggle on or off, hardcoded subtitles become part of the visual content. This means the text will always appear on screen regardless of the platform, device, or media player used to view the video.

Hardcoded subtitles are sometimes called "burned-in" or "open" subtitles because they're baked into the video during the encoding process. Once rendered, they cannot be turned off, edited, or removed without re-editing the original video file. This permanence has both advantages and limitations depending on your specific use case.

Why Content Creators Choose Hardcoded Subtitles

The rise of social media has dramatically increased demand for hardcoded subtitles. Platforms like Facebook, Instagram, LinkedIn, and Twitter autoplay videos without sound by default, meaning viewers scroll past silent videos unless captions catch their attention. Studies show that 85% of Facebook videos are watched without sound, making visible subtitles essential for engagement.

Hardcoded subtitles also solve compatibility issues that plague soft subtitles. Different platforms handle caption files differently—YouTube supports SRT uploads while Instagram doesn't accept external subtitle files at all. By burning subtitles directly into your MK3D video, you guarantee consistent display across every platform where your content appears.

Best Practices for Professional-Looking Subtitles

Creating effective hardcoded subtitles involves more than accurate transcription. Font choice matters—sans-serif fonts like Arial or Helvetica remain legible even at smaller sizes on mobile devices. Position your subtitles in the lower third of the frame where they're expected, but avoid covering important visual elements. A semi-transparent background box behind the text improves readability against varying backgrounds.

Keep subtitle lines concise. Industry standards recommend no more than two lines with roughly 42 characters per line. Each subtitle should remain on screen long enough to read comfortably—typically at least 1.5 seconds. Sonix automatically formats your transcripts following these best practices, splitting text intelligently so your Matroska 3D Video File subtitles look polished and professional.

When to Use Hardcoded vs. Soft Subtitles

Choose hardcoded subtitles for social media content, advertisements, promotional videos, and any content distributed across multiple platforms. They're also ideal when you want complete control over the visual presentation of your captions, including custom fonts, colors, and positioning that match your brand guidelines.

Soft subtitles work better for long-form content on platforms that support them, like YouTube or streaming services. They give viewers control and allow you to offer multiple language tracks without creating separate video files. Many creators use both approaches—hardcoded versions for social media clips and soft subtitles for full-length videos on YouTube. Sonix exports to both SRT/VTT files and burned-in MK3D videos, giving you flexibility for any distribution strategy.