[FFmpeg-user] How can I convert mpeg2 5.1 audio to ac3?

[bluesky at caramail.com]

"Carl Eugen Hoyos" <cehoyos at ag.or.at> wrote:

>> My computer is connected to my receiver via a
>> S/PDIF (Toslink optical) cable

> What does your receiver show when you play with
> MythTV, what does it show for XBMC?
> Maybe one is "Dolby Digital" (which is unrelated
> to PLII) and one doesn't show it / shows PLII?

I have never heard of "PLII" prior to this thread.  MythTV tells me nothing about the audio, it simply reports it as 1080 and that's all, unless there is some hidden display option I don't know about.  XBMC reports it as "1080" "MPEG-2" "2.0" "MP3" "1.78"

> Do you have a switch to change between "Stereo"
> and "PLII":

No.

> My receiver has such a switch and
> it helps if I reencode the PLII stream to Dolby
> Digital with FFmepg:
> $ ffmpeg -i input -ab 640k out.ac3

At least on my system, XBMC won't even acknowledge the presence of a file with a .ac3 extension.  If I change it to .mp4 then XBMC will play it but in exactly the same way it plays the .ts file - there is no discernable difference.

> I can still here the surround via S/PDIF if I
> tell my receiver that this is PLII.

My receiver has options for THX, Dolby/DTS Surround, Stereo, and Direct.  Stereo and Direct play with no audio at all from the back channels, while THX and Dolby both play the file the same way I have described previously.  I usually leave it set on THX.