[FFmpeg-user] AC-3 Dolby Digital 5.1 Encoding

[Joshua Tidsbury]

On 2012-05-26, at 11:14 AM, "Carl Eugen Hoyos" <cehoyos at ag.or.at> wrote:

> This is certainly a possibility, but I since I tested many 
> (including unusual) layouts with ffmpeg and a receiver / 
> hardware decoder and I do not remember a case where 
> specifying the layout was really necessary:
> Could you provide an example where it is necessary?
> (except raw pcm input, of course)
> 
> There may be bug in the default behaviour that can be fixed.
> 
> Carl Eugen

To be honest, I don't have an example. Only many years of experience as a broadcaster that has led me never to trust anything associated with the words "default" and "Dolby" in the same sentence :)

We always explicitly define all metadata flags for every encode as its the only way to reasonably expect the playback behaviour to be appropriate, especially with regards to dialnorm, mixdown coefficients, and compression methodologies. I suppose explicitly defining the output format mostly stems from the use of Dolby's hardware encoders.

Thanks!
Josh