Of those 3 (Happy Otter, Handbrake, VideoRedo), which would you recommend for 5.1? I've the same problem as the OP. Is there a way to convert a project so it can be opened and rendered by older, AAC enable versions? For example, can I convert my VP19 project to VP15 for rendering?

"... can I convert my VP19 project to VP15 for rendering??

No.

"Of those 3 (Happy Otter, Handbrake, VideoRedo), which would you recommend for 5.1?"

I use all three. Start with Handbrake since it's free, then invest in your tools as you go along.

You haven't described your media. I might use a different tool for different media. I don't have a problem injesting old hat camera files from the past with Vegas 19.

I rarely output 5.1 audio.

You can export your audio and import it into an older version. I do that for all of my AC3 needs.

@Rene-Fortin @Den24601 As an alternative to (Happy Otter, Handbrake, VideoRedo) you can install Voukoder plugin to render faster than most Vegas default templates, Voukoder supports 5.1 AC3.

Although a 5.1 AC3 render via voukoder in Vegas 19 is rendered correctly, and does play 5.1 via a standard player (and also before rendering on the timeline); I noticed that importing back that 5.1 ac3 rendered mp4 delivery file in vegas 19, it only plays in stereo on the timeline (project setting is 5.1). Not sure it is a bug, not supported or if I am doing something wrong...

'You can export your audio and import it into an older version'

For example, export VP19 surround-audio using what format to bring it into VP15? I then render just the audio as 5.1 using VP15 and rejoin with the video?

Bitman, if you import that mp4 Voukoder created file into an ac3 enabled Vegas, like VP15, does that problem with stereo still exist?

You can export your audio and import it into an older version. I do that for all of my AC3 needs.

Yes, that is what I do as well - but back into VP16 with the AC3 workaround which works well if you've got DVD Architect 5.2 or 6 installed in order to get the AC3-Pro dll. Early versions of MAGIX Vegas Pro had a basic version on AC3 5.1 but that completely went with VP17 (I think it was)

Also, a couple of considerations. I only copy/paste the audio tracks from the more recent Vegas Pro versions back to VP16, but all the audio events must be ungrouped from their video events otherwise the video events will also paste which can upset things in VP16 because my VP16 project has only been set up for audio tracks. And the other thing is that I place a short zero level audio event at the head and tail of every audio track because I've found that's the only way to successfully copy/paste the audio tracks (only) over to VP16.

Of course, any audio FX or 5.1 / 2.0 settings at track level need to be set again in the earlier VP version because copy/paste won't copy those settings across from the later version.

@Den24601 @Dexcon I currently have VP19 post, VP18 post and VP17 installed, I removed prior versions to save space and "move on" as it were, and will probably remove 17 as well in the near future. So unfortunately I cannot try it on VP16. I am not going to reinstall 16,14, 13 as this may upset things software wise, you never know.

Why that the Vegas cannot play an imported 5.1 ac3 (plays only downmixed stereo), that is beyond me, If I am not mistaken/recall from one of the older posts it is because the devs say it is because Vegas uses windows system to decode/play, and as such 5.1 ac3 is not possible; but windows 10 can and does play 5.1 ac3 in their player, so that does not make sense...

The Vegas developers could add 5.1 ac3 import/play (+ export without third party plugins) and tout as a "new feature" as part of their new delivery strategy!

And possibly asking a small fee for Dolby license if needed...

By the way, this post thread should be moved to audio section of this forum.

@bitman please read @VEGASDerek here.