I have this old Blu-ray rip where I only included the lossless DTS-HD MA audio track. This will from time-to-time cause issues with incompatible clients so I would like to include the lossy DTS audio track as well. Now I can’t find the Blu-ray but I was under the impression that I should be able to use for example Handbrake to convert the audio?
I’ve extracted the audio to a .MKA file but importing it into Handbrake tells me that the file is not recognized…
How can I convert the audio to a lossy format that I can include in the .MKV file?
Probably no need to convert. The lossy DTS “core” is always a part of a DTS HD-MA track.
If you simply want to get rid of the lossless part, you can remux the file using MKVtoolnixGUI.
Drag the source file in, then select the DTS HD-MA audio track.
On the right side scroll down to “Audio properties”. Tick the checkbox “Reduce to core” and start the muxing procedure.
Another method would be to use ffmpeg (or its GUI XMedia Recode - Free All-in-One video and audio converter to convert the DTS HD-MA track to a lossy format. I recommend AAC stereo or Opus stereo.
If you want to retain the surround sound, you can also pick ac3 if you want.
I recommend creating just the audio track. Inserting it into your file is easier to understand if this process is kept as a separate step.
I personally use again MKVtoolnix for that kind of thing.
Just drag in your original file, and the converted audio track.
Tag, and name as required. Reorder the track if need be, to be before the lossless track.
That way it may get selected over the lossless track by the automatic track selection or by users who don’t care about it.
Here is an example of one I recently did. I left the lossy core DTS in there, and used the lossless in a separate step to mixdown to stereo and convert to AAC.
Optional (but very much recommended) when downmixing to stereo: analyze the mixed down track and apply normalization. That way you can avoid the “too quiet” issue on most clients. This can also be done during the mixdown+conversion in ffmpeg or XMedia Recode.
Yes, it happens frequently when playing a 5.1 (or higher) audio track on a device that only supports stereo.
Or when reducing the channel count during transcoding.
It’s caused by the method of mixing the signal from all 6 channels to just 2 channels.
In order to avoid digital clipping, all channels are made quieter before the mixdown. The mixer doesn’t know how loud each channel actually is, so this attenuation is a fixed value that avoids clipping even in the case when all source channels would have full signal. But that is very rarely the case in movie sound.
