Feature request: center channel boost on downmix

[frankvw]

I absolutely love Handbrake.

However, one feature I really would like to see incorporated in Handbrake is an option to boost the center channel when downmixing to 2.0. Many movies that are downmixed from 5.1 suffer considerably because the dialogue tends to get drowned in background sounds. I have run tests myself, comparing 5.1 movies played on Kodi with a 6db center channel boost vs. the same movie downmixed to 2.0 with Handbrake, and frequently the difference is dramatic. Using Handbrake's DRC may sometimes help a little, but not when dialogue is being delivered on the center channel in the presence of higher levels of non-dialogue audio on other channels.

Currently the only workaround is to incorporate the original AC3 soundtrack in passthru mode which preserves the 5.1 surround sound and thus allows the player (e.g. Kodi) to boost the center channel, but this defeats the entire purpose of Handbrake's downmixing features.

Please, pretty please, with sugar on top...

// FvW

[Deleted User 13735]

Duplicate removed by user.

[Deleted User 13735]

. I have run tests myself, comparing 5.1 movies played on Kodi with a 6db center channel boost vs. the same movie downmixed to 2.0 with Handbrake, and frequently the difference is dramatic.

That's correct. You cannot boost the center channel in a 2 channel mixdown. It's already been boosted 4 db, to -27 Dialnorm by the original Dolby encoder. It is not a function of DRC, which is basically a compression flag.

You would need to catch the Dolby DL flag pre-encode and adjust dialog normalization manually before downmix, which "may" exceed Handbrake's narrow purposes, which are arguably not as a nonlinear editor.

A properly set up stereo system does not need additional normalization, and comparing to artificially boosted 5.1 from a player is not a fair test of even a preferential model, which is what you seem to be asking for.

However, running your 5.1 amp at "DSP All Channel Stereo" (better than Dolby PLII) will refocus dialog back to the center of your sound field, which may be what your ears are actually missing.

If you are interested in learning about Dolby metadata, the White Paper us here:
https://www.google.com/url?sa=t&source= ... JvnYcFxZ0y