Misuse of "AC3 Passthru" ?

[Corp]

So, I think I've been making a critical error. Using MakeMKV to backup my discs, I then run them through handbrake.

I have been using "AC3 Passthru" for every movie no matter what the original audio source, including DTS, because I wanted AC3 5.1 as the final product.

The codec information in VLC afterwards shows AC3 (A52 - Channels 3F2R/LFE), but some of the movies don't seem to be 5.1 surround.

Have I been screwing up all my DTS movies by doing this? If so, is there a way to fix them? Or do I need to start over?

Thanks!

[leghorn]

AFAIC you'll have to start over again. IMHO "passthru" means to pass something on unchanged. So if you choose "AC3 passthru" but have DTS, you cannot pass AC3 on to your encoded file. You could either choose "auto passthru" which leaves the audio unchanged. So with DTS you'll end up with DTS. Or in case you have DTS audio but want AC3, you should choose to convert to AC3.

[Vidd]

You don't need to encode the video again in Handbrake. You can fix it by demuxing / muxing. You may have to use MakeMKV again if you deleted the files.

Use MKVToolNix (mkvmerge). Drag both the Handbrake created mkv and the MakeMKV created mkv. Only select the Handbrake video the DTS audio from the MakeMKV file. And select any subtitles if you have them. Make sure the Handbrake mkv audio is deselected as well as the MakeMKV video.

This will mux the Handbrake encoded video with the original DTS.

[johns0]

The op doesn't want dts,just 5.1 ac3,most likely handbrake encoded the dts as aac as a fallback since it didn't see any ac3 audio.Use eac3to convert any of the original mkv to 5.1 ac3 and then mux the audio with the re-encoded mkv and deselect the screwed up audio.If you don't have the original mkv then rip it again with makemkv.

[Corp]

Thanks for the info guys, I think I might just start over

I might try to pass them through HB again with low video settings and set the audio to DTS passthrough. Since it is suppose to preserve maybe it's just a label at that point (DTS or AC3). Then recode to AC3 and use Vidd's trick posted above. Who know's, might work....