Proper 5.1 audio conversion (AC3 mkv->AAC mp4)

[rgr]

I have files in an MKV container with the following audio track:

ID: 2
Format: AC-3
Format/Info: Audio Coding 3
Commercial name: Dolby Digital
Codec ID: A_AC3
Duration: 49 s 952 ms
Bit rate mode: Constant
Bit rate: 448 kb/s
Channel(s): 6 channels
Channel layout: L R C LFE Ls Rs
Sampling rate: 48.0 kHz

I convert them to MP4 (H264+AAC) using the AviSynth script (audio passthrough) and get the following audio:

Format: AAC LC
Format/Info: Advanced Audio Codec Low Complexity
Codec ID: mp4a-40-2
Duration: 49 s 952 ms
Source duration: 49 s 973 ms
Source_Duration_LastFrame: -11 ms
Bit rate mode: Constant
Bit rate: 192 kb/s
Channel(s): 6 channels
Channel layout: L R C Cb Lb Rb
Sampling rate: 48.0 kHz

Is this channel conversion correct? (L R C LFE Ls Rs -> L R C Cb Lb Rb)?

When I try to open the output MP4 in VDub I get "FFMPEG: Unsupported channel layout".

[cholla]

I believe VDub is telling you that the FFMPEG version you have does not understand the L R C Cb Lb Rb channel layout.
This may be for any FFMPEG version but I'm not sure about this.
The FFMPEG codecs need to have the code to understand this channel layout to work with it.

Why not use FFMPEG command line?
Or maybe Clever to do this conversion?

[videoAI]

I would use Clever instead of vdub ..
and update FFmpeg to 8.x

[rgr]

I would use Clever instead of vdub ..
and update FFmpeg to 8.x

Vdub is for testing. I open the source mkv in AviSynth.