Should you choose Passthrough or Transcoding when creating a 4K UHD Blu-ray?

 

At first, the answer may seem obvious. Passthrough avoids video re-encoding, so it preserves the original encoded video and finishes much faster. Transcoding creates a new video stream, takes longer and may introduce some generational compression. But in real 4K UHD Blu-ray authoring, the decision is more complicated.

 

Your source may be too large for a burned BD50. A Dolby Vision MKV may require conversion before it becomes suitable for UHD Blu-ray. An MKV containing TrueHD audio cannot simply pass the TrueHD stream through, because Blu-ray requires the corresponding Dolby Digital AC3 companion audio. And although commercial UHD Blu-ray movies can use 66 GB or 100 GB read-only media, that does not mean a standalone UHD Blu-ray player will reliably read a user-burned BDXL disc. The Blu-ray Disc Association identifies 66 GB and 100 GB UHD movie media as read-only formats, while real-world reports show inconsistent support for burned BDXL media in standalone players.

 

For these reasons, Passthrough is not automatically the best mode even when the source video itself is compatible.

 

Yuhan 4K UHD Creator provides both Passthrough and Transcoding modes so that the processing method can be selected according to the source and the intended playback method.

 

This guide explains exactly when each mode should be used.

Part 1. Passthrough vs Transcoding: The Short Answer

If you only want a quick recommendation, use this rule:

 

Situation	Recommended Mode
UHD Blu-ray compliant M2TS from an existing UHD disc	Passthrough
You want to keep the original encoded video unchanged	Passthrough
Source video does not meet UHD Blu-ray specifications	Transcoding
Video is too large for the target disc	Transcoding
Dolby Vision Profile 8 MKV or MP4	Transcoding
Dolby Vision Profile 7 M2TS from UHD Blu-ray	Passthrough or Transcoding
You need to change resolution or frame rate	Transcoding
You want to compress the video but keep TrueHD/Atmos or DTS-HD MA	Transcoding + Audio Copy

 

This distinction prevents one of the most common mistakes in UHD Blu-ray authoring: choosing Passthrough simply because it sounds more “lossless,” even when the source structure is not suitable for a standards-compliant physical disc.

 

What Is Passthrough Mode?

Passthrough means that compatible encoded streams are used without decoding and re-encoding the video. Think of it as reorganizing already compliant media into a new Blu-ray structure rather than creating a new video encode from scratch.

 

If your source HEVC video is already suitable for UHD Blu-ray, there is little reason to encode the same picture again. Passthrough avoids that unnecessary generation. This provides two major benefits.

 

The first is quality preservation. Because the video is not re-encoded, there is no additional compression generation introduced by the authoring process. The second is speed. Remuxing compliant video is normally much faster than decoding every 4K frame and encoding it again.

 

However, Passthrough comes with an important restriction: the source must already be appropriate for the target Blu-ray format. Yuhan's existing processing-mode documentation similarly distinguishes Passthrough as direct stream handling that requires source media to comply with Blu-ray or UHD Blu-ray specifications.

 

What Is Transcoding Mode?

Transcoding works differently. The source video is decoded and then encoded into a format that fits the Blu-ray or UHD Blu-ray output requirements. That makes Transcoding much more flexible. For example, suppose you have a 4K MKV whose video dimensions, codec parameters or HDR structure are unsuitable for direct UHD Blu-ray authoring. Rather than rejecting the source, a transcoding workflow can convert the video into an appropriate UHD Blu-ray stream.

 

Transcoding can also reduce bitrate. This matters when a large source does not fit your selected disc capacity. Yuhan 4K UHD Creator supports BD25, BD50, BD66 and BD100 output, so the appropriate encoding decision can also depend on which disc size you plan to use. The trade-off is that encoding takes substantially more processing than Passthrough and creates a new video generation. That does not mean the result necessarily looks poor. With an appropriate bitrate and good encoder, visual differences can be very small. But technically, the video has been encoded again.

 

Passthrough vs Transcoding Quality

From a purely technical perspective, Passthrough wins when the original video is already suitable.

If the video bitstream is copied unchanged, no new compression artifacts can be introduced by video encoding.

Transcoding must create a new compressed video stream.

However, it is misleading to conclude that Transcoding always produces visibly bad quality.

Modern HEVC encoding at an appropriate UHD bitrate can retain excellent visual quality. Whether you can actually see a difference depends on the source, bitrate, encoder, display size, viewing distance and content.

High-motion content, grainy film material and complex dark scenes generally require more bitrate than clean, static material.

Therefore, the real decision is usually not:

Lossless vs bad quality

but rather:

Do I need to encode this source at all?

If no, use Passthrough.

If yes, use a high-quality Transcoding workflow.

 

Passthrough vs Transcoding Speed

Passthrough is normally much faster because the software does not need to encode every video frame again.

This can make an enormous difference with 4K HEVC.

Transcoding a feature-length UHD movie requires decoding the source, processing its frames and encoding an entirely new 4K stream.

Hardware acceleration can reduce that processing time considerably. Yuhan's current UHD Creator page lists GPU acceleration using technologies including NVIDIA, Intel and VideoToolBox on macOS.

But even with hardware acceleration, Transcoding still performs fundamentally more work than Passthrough.

If your source is already compliant, Passthrough therefore saves both time and unnecessary encoding.

 

 

Part 2. Why Passthrough Is Not Always the Best Choice

The word “Passthrough” is attractive because it suggests no quality loss. That is true only when the source is already suitable for the target format. Imagine that you have a beautiful 4K HEVC MKV. It plays perfectly on your PC and television. That does not automatically mean its video stream is ready to be placed directly onto an Ultra HD Blu-ray.

 

Files created for streaming, Plex, Kodi, Infuse or ordinary file playback are not necessarily structured in the same way as a standards-based UHD Blu-ray.

 

Resolution is one example. A movie stored in an MKV may have been cropped to 3840 × 1600 because the black bars were removed during encoding. That may be perfectly reasonable for file playback, but it is not the same thing as a standard 3840 × 2160 UHD Blu-ray video frame. In such a situation, transcoding is the safer authoring workflow. The same principle applies to unusual frame sizes, incompatible encoding parameters and some Dolby Vision configurations.

 

A source can be an excellent 4K video file without being an appropriate Passthrough source for UHD Blu-ray.

 

Passthrough Is Ideal for UHD Blu-ray M2TS Sources

One of the best candidates for Passthrough is an M2TS stream extracted directly from an existing UHD Blu-ray.

 

Why?

 

Because the original video was already encoded for UHD Blu-ray. Assuming the stream has not been altered and you do not need to compress it, re-encoding it would normally be unnecessary. This is especially relevant for high-quality archival or personal re-authoring workflows where you want to reorganize content, select specific audio/subtitle tracks or create a different disc structure while keeping the original encoded picture.

 

For Dolby Vision sources, M2TS is also particularly important because UHD Blu-ray Dolby Vision Profile 7 uses a disc-oriented dual-layer structure. Yuhan's current Dolby Vision guide states that a dual-layer Dolby Vision M2TS extracted from UHD Blu-ray can use either Passthrough or Transcoding. If the source already fits the target capacity, Passthrough is usually the logical starting point.

 

Part 3. Why Dolby Vision MKV and MP4 Usually Need Transcoding

This is where the Passthrough vs Transcoding decision becomes especially important. Dolby Vision is not stored identically in every container and profile. A Dolby Vision MKV or MP4 may contain a single-layer Dolby Vision stream—commonly Profile 8—while UHD Blu-ray uses a disc-compatible Dolby Vision structure based around Profile 7.

 

Therefore, simply copying the video from the MKV into a UHD Blu-ray structure would not convert it into the required disc structure. Yuhan's current Dolby Vision documentation specifically recommends Transcoding for Profile 8 MKV/MP4 sources, while dual-layer Profile 7 M2TS sources can use Passthrough. This is a very important distinction. A Dolby Vision file may play correctly in an MKV-compatible media player while still requiring conversion before it can become a Dolby Vision UHD Blu-ray.

 

So the correct question is not:

 

“Does my source already contain Dolby Vision?”

 

It is:

 

“Is the Dolby Vision structure in my source appropriate for UHD Blu-ray?”

 

If the answer is no, Transcoding and profile conversion are necessary.

 

What About HDR10 and HDR10+?

HDR by itself does not mean you must use one specific processing mode. The choice still depends on whether the underlying video stream is suitable for the target UHD Blu-ray. Yuhan 4K UHD Creator currently lists support for HDR10, HDR10+ and Dolby Vision in both Passthrough and Transcode workflows.

 

Therefore, if you have a standards-compliant HDR10 UHD source and do not need to change its video, Passthrough may be appropriate. If the source requires resizing, bitrate reduction, format conversion or other video changes, Transcoding is the appropriate workflow. The key is to separate two questions:

 

What HDR format does the source use?

 

and

 

Does the video itself comply with the output requirements?

 

They are related, but they are not the same question.

Part 4. Passthrough Cannot Shrink a Large Video

Another major limitation of Passthrough is file size. Suppose your selected video, audio and subtitle streams require around 70 GB. If your target is BD100, that may not be a problem.

 

But if you want the project to fit on BD50, simply selecting Passthrough cannot magically reduce the encoded video to 50 GB. The whole point of Passthrough is to avoid re-encoding. To substantially reduce the video size, the bitrate needs to be reduced, which means creating a new encode.

 

That requires Transcoding. Yuhan's Dolby Vision workflow documentation similarly notes that Transcoding can be used when a large UHD source must be compressed to a smaller disc capacity, whereas Passthrough does not perform that compression.

 

So if your first priority is:  Preserve the exact encoded video.

 

choose a large enough disc and use Passthrough when the source is compliant.

 

If your first priority is: Fit this movie onto BD50. Transcoding may be unavoidable.

Part 5. Does Transcoding Mean You Have to Lose Dolby Atmos?

No. This is one of the most useful distinctions in a modern Blu-ray authoring workflow. You may need to transcode the video without wanting to re-encode the audio. For example, imagine an MKV containing: 4K HEVC video that needs transcoding and TrueHD with Dolby Atmos that is already suitable for Blu-ray.

 

Re-encoding the TrueHD track would provide little benefit and could destroy the original lossless audio stream. This is where Audio Copy becomes useful. Yuhan 4K UHD Creator can retain compatible EAC3, Blu-ray PCM, TrueHD/Dolby Atmos and DTS-HD Master Audio through Audio Copy or Passthrough. That gives you a useful hybrid workflow:

 

Transcode the video + copy the original audio.

 

You can therefore reduce or convert the video while preserving the original high-quality soundtrack.

 

Part 6. Passthrough vs Audio Copy: They Are Not the Same Thing

These two terms are sometimes confused. Passthrough refers to the processing mode for compliant media streams.

 

Audio Copy is useful when the video needs transcoding but the selected audio stream can remain unchanged.

 

For example:

• Source video: 3840 × 1600 HEVC
• Audio: TrueHD Dolby Atmos

 

The video may need to be transcoded to a proper UHD Blu-ray frame structure. But the Atmos audio does not necessarily need to be re-encoded. You can therefore select Transcoding for the project and enable Audio Copy for the compatible audio. Yuhan's dedicated Audio Copy documentation describes exactly this use case: video can be transcoded while compatible AC3, EAC3, DTS, DTS-HD Master Audio, TrueHD or Blu-ray PCM audio is retained. For home-theater users, this can be a better compromise than either “copy everything” or “re-encode everything.”

 

Part 7. How to use the Passthrough mode or Transcoding mode in Yuhan 4K UHD Creator

Before we start, we need to download and install Yuhan 4K UHD Creator. If your computer is Windows, you can click the button on the left below to download it. If your computer is Mac, please click the button on the right below to download it.

 

       

 

If you’re using a Mac with an Apple Silicon chip (M1, M2, M3, M4, etc.) rather than an Intel processor, please download the native Apple Silicon version here:

https://yuhanmedia.com/wp-content/download/bdc_setup_apple.dmg

Step 1: Import Video Files

Launch Yuhan 4K UHD Creator, click the "4K UHD" tab at the top, and then click "Add Video" to load your video files. Once loaded, you can select the desired audio tracks and subtitles for each video. At the bottom of the interface, you can also configure the disc capacity and frame rate.

 

Step 2: Set video (optional)

Click the edit icon next to the video item to open the video settings window. From there, you can trim the video by adjusting the start and end times, or set up chapters manually. If the video already includes chapter data, the software will import it automatically.

 

Step 3: Select a menu template and customize it.

Click "Select Menu" to open the settings. Choose a template from the right panel to get started, then customize it by changing the background image or audio. You can even use a video background for an animated disc menu.

 

 

Step 4: Advanced Settings

Open the software's settings window; you can configure the passthrough mode or transcoding mode via the "Blu-ray and UHD Processing Mode" option.

 

Step 5: Output Settings

Click the Start button in the main window to open the output settings window. From here, you can choose to save the UHD Blu-ray as a BDMV folder or ISO file, or burn it directly to a disc. You can also configure preferences such as default audio tracks and subtitles, and set the computer to shut down automatically once the process is complete.

 

 

Step 6: Start authoring

Click the "Start" button in the settings window to begin creating the UHD Blu-ray. The process is complete once the disc ejects.

 

Part 8. Five Real-World Examples

Example 1: 42 GB UHD M2TS for a BD50

You have a 42 GB M2TS extracted from an UHD Blu-ray.

Its HEVC video is already suitable for UHD Blu-ray, its audio structure is compliant and the completed project still fits on a BD50.

You want to burn it for playback on a standalone UHD Blu-ray player.

Recommended mode: Passthrough

There is no need to encode the video again.

Example 2: 72 GB UHD M2TS for a Standalone Player

You have a compliant 72 GB UHD M2TS.

From a video-compliance perspective, it could be passed through.

However, your goal is to create a physical disc for a standalone UHD Blu-ray player.

Because reliable playback of user-burned BDXL media should not be assumed, your practical target is BD50 or BD25. Real-world BDXL playback reports vary significantly between standalone players.

The project therefore has to be compressed.

Recommended mode: Transcoding

Example 3: 72 GB UHD M2TS for ISO Playback

Now take exactly the same source.

This time, you do not need a physical disc. You only want a full-size ISO for playback from storage using a compatible playback environment.

There is no need to force the video under the BD50 capacity limit.

Recommended mode: Passthrough

The source can remain at its original encoded bitrate.

Example 4: 35 GB MKV with TrueHD Dolby Atmos

You have a 35 GB MKV containing compliant-looking HEVC video and a TrueHD Dolby Atmos track.

The project easily fits on BD50.

It may therefore seem like a perfect Passthrough candidate.

But it is not.

The MKV contains TrueHD without the complete Blu-ray AC3 + TrueHD structure required for authored disc playback.

Recommended mode: Transcoding

Yuhan can retain the TrueHD audio and automatically create the necessary AC3 companion audio during authoring.

Example 5: Dolby Vision Profile 8 MKV

You have a MakeMKV-derived or otherwise prepared MKV containing Dolby Vision Profile 8 and TrueHD Atmos.

You want to create a Dolby Vision UHD Blu-ray.

The Dolby Vision structure must be converted to the disc-oriented workflow, and the TrueHD audio also requires the appropriate Blu-ray companion structure.

Recommended mode: Transcoding

This is a good example of why “no re-encoding” should never be chosen simply because the original file already looks excellent.

Part 9. Frequently Asked Questions

Does Passthrough provide better quality than Transcoding?

Passthrough keeps the compatible original encoded video unchanged, so it does not introduce another video encoding generation.

However, it can only be used when the source and intended output allow it.

Can I use Passthrough for a 70 GB M2TS?

Yes, if the source is compliant and you are creating a large ISO for compatible file-based playback.

If you want to burn the project to BD50 for reliable standalone UHD Blu-ray player playback, you need Transcoding to reduce the project size.

Can I burn a 70 GB movie to a BDXL disc instead?

Recordable BDXL media exists, but standalone UHD Blu-ray player support is inconsistent and should not be assumed. Commercial 66 GB and 100 GB UHD Blu-ray releases use read-only disc formats defined by the UHD Blu-ray specification, not ordinary consumer-recordable BDXL in the same sense.

For a burned disc intended for a standalone player, BD25 or BD50 is the safer practical target.

Can an MKV containing TrueHD use Passthrough?

No, not in the Yuhan UHD Blu-ray authoring workflow.

A typical MKV contains the extracted TrueHD stream without the complete Blu-ray AC3 companion structure. Blu-ray TrueHD playback uses companion Dolby Digital audio for compatibility.

Use Transcoding mode. Yuhan can retain the TrueHD track and generate the required AC3 companion audio.

Will I lose Dolby Atmos if I use Transcoding?

Not necessarily.

For supported TrueHD Dolby Atmos sources, Yuhan can preserve the original TrueHD audio while creating the AC3 + TrueHD structure required by the authored Blu-ray.

Can a Dolby Vision MKV use Passthrough?

A Dolby Vision Profile 8 MKV that needs to become a standards-oriented Dolby Vision UHD Blu-ray requires conversion, so use Transcoding.

A suitable disc-originated Dolby Vision Profile 7 M2TS may be used with Passthrough when it is otherwise compliant and does not need to be compressed.

Can I use menus with Passthrough?

Yes.

Menu authoring and video processing mode are separate parts of the workflow. You can use Passthrough for compliant video while still creating a complete UHD Blu-ray structure with menus, chapters, audio tracks and subtitles.

Part 10. Conclusion

assthrough and Transcoding are not two quality presets. They are two different authoring workflows.

 

Use Passthrough when the source is already suitable for UHD Blu-ray, no structural conversion is required, and you do not need to reduce the video size.

 

This is especially useful for compliant M2TS sources, smaller physical-disc projects and large ISO-only projects where retaining the original encoded video is the priority.

 

Use Transcoding when the source must be changed before it can become the UHD Blu-ray you need. 

 

That includes projects that must be compressed to BD25 or BD50, non-standard video sources, Dolby Vision files that require profile conversion and MKV files containing TrueHD audio. 

 

For physical UHD Blu-ray playback, the disc-capacity question should be considered at the very beginning. Commercial UHD Blu-rays may use 66 GB or 100 GB read-only media, but user-burned BDXL support among standalone players is not something an authoring workflow should rely on.

 

Therefore, when creating a burned UHD Blu-ray for a standalone player, BD25 or BD50 should normally be the target. If the source is too large, Transcoding is the correct solution.

 

If you are creating an ISO instead, that physical capacity restriction disappears, and Passthrough becomes practical for much larger compliant sources.

 

The same principle applies to audio and HDR. Do not choose Passthrough simply because your source is 4K HEVC. Check its Dolby Vision profile, TrueHD structure, frame dimensions, bitrate, final project size and intended playback device first.

 

Once those factors are understood, the choice between Passthrough and Transcoding becomes straightforward—and you can avoid unnecessary encoding without sacrificing the compatibility required by the final UHD Blu-ray.

 

If you want to learn more about Yuhan 4K UHD Creator, please click: https://yuhanmedia.com/uhd-creator

 

If you want to download and try it for free, please click the button below to download it.

 

       

 

If you’re using a Mac with an Apple Silicon chip (M1, M2, M3, M4, etc.) rather than an Intel processor, please download the native Apple Silicon version here:

https://yuhanmedia.com/wp-content/download/bdc_setup_apple.dmg