Convert MKV DTS to AC3

[PaddyC13]

Hi Folks,

I am new to MakeMKV so please be patient with me!

I have extracted/ripped (not sure what the correct term is) a few of my DVDs successfully so I thought it was worth trying to copy one of my BluRays to an MKV file. I am placing the converted MKV files on to my Synology NAS and accessing them through their DS Video application.

All is working fine until I converted my Tora Tora Tora BlueRay to an MKV but it would not play via DS Video (VLC had no issue). A wee bit of digging and I found out that the issue is that the audio on this film is in DTS 5.1 which Synology do not support in their apps (licensing issue apparently).

I have looked through MakeMKV but I cannot see an option to convert audio from DTS 5.1 to AC3 (which DS Video does support). No doubt the answer is staring me in the face but I cannot see the wood for the trees at present.

Could someone please point me in the right direction?

Thank you for your help.

Kind regards

Paddy
UK

[wmcclain]

I do that sort of thing outside of makemkv.

Do you have ffmpeg? It's free.

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ffmpeg -i input.mkv -c:v copy -c:a ac3 -b:a 640k -c:s copy output.mkv

This will convert the audio and retain the same video and subtitles. First audio and subtitle tracks only, I presume.

Should be pretty fast.

[PaddyC13]

Hi @wmcclain

Thank you for your swift reply - it is much appreciated. I have not heard of ffmpeg so will Google it tomorrow, hopefully locate it and give a go.

I will report back!

Many thanks

Paddy
UK

[PaddyC13]

I do that sort of thing outside of makemkv.

Do you have ffmpeg? It's free.

Code: Select all

ffmpeg -i input.mkv -c:v copy -c:a ac3 -b:a 640k -c:s copy output.mkv

This will convert the audio and retain the same video and subtitles. First audio and subtitle tracks only, I presume.

Should be pretty fast.

Hi @wmcclain,

That worked perfectly, thank you very much.

I did hit anouther issue with the subtitles as guess what, Synology DS Video does not support the PGS format either!

Managed to locate an SRT file so that is fixed too.

It is getting to the point where I need to switch to a different media server such as Plex - is that a good choice?

Once again, thank you for your help.

Kind regards

Paddy
UK

[wmcclain]

Sorry, I don't use Plex (or anything so sophisticated).

I asked Grok, which says:

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Yes, the Plex Media Server handles PGS (Presentation Graphic Stream) subtitles, which are image-based subtitles commonly found in Blu-ray rips. However, support is not universal across all Plex clients and often requires transcoding the video stream to "burn in" the subtitles, depending on the playback device. This can increase server CPU usage and limit simultaneous streams.

### Key Details on PGS Subtitle Handling:
- **Detection and Compatibility**: Plex detects embedded PGS subtitles in media files (e.g., MKV containers) and lists them as available tracks during playback. External PGS files (typically .sup/.idx pairs) are also supported if named correctly (e.g., `Movie (2010).sup` alongside `Movie (2010).mkv`).
- **Direct Play vs. Transcoding**:
  - **Direct Play**: Possible on clients that natively support PGS rendering, such as:
    - Plex Desktop (Windows/Mac/Linux).
    - Android/Android TV apps.
    - Apple TV 4K app.
    - Some smart TVs (e.g., LG webOS, certain TCL Google TV models).
    - In these cases, no transcoding is needed for subtitles if video/audio also direct plays.
  - **Transcoding Required**: Common on clients without native PGS support, like Roku devices, some Samsung TVs, or older smart TVs. Plex burns the subtitles into the video stream, which forces a transcode even if the video/audio could otherwise direct play.
- **Recommendations for Better Compatibility**:
  - Use text-based SRT subtitles (downloaded via Plex's built-in OpenSubtitles integration or tools like Bazarr) for broader direct play across all clients without transcoding.
  - Ensure your Plex Media Server is updated (v1.20+ for optimal subtitle detection).
  - Test playback on your specific client to confirm behavior, as support can vary by app version and hardware.

For the most current details, check Plex's official support article on local subtitles.

[dcoke22]

Regarding Plex and PGS subtitles, it depends on the capabilities of the client as wmcclain's Grok output indicates. I use the Plex app on an AppleTV 4K and it displays them using Direct Play (without transcoding).