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

bluesky at caramail.com bluesky at caramail.com
Tue Nov 4 23:36:42 CET 2014

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

> > What does your receiver show
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Sorry, I misread that.  When playing the test file, in MythTV it depends on whether I have THX or Dolby selected (it plays the channels correctly in either).  It either shows:
THX Cinema 3/2.1
Dolby D 3/2.1

But in XBMC, no matter which of the two are selected, it simply says:
PCM 48kHz

> I know (expected) that MythTV and XBMC do not show
> PLII. My receiver has a display and when digital
> audio (as via S/PDIF) starts, it shows something
> on this display.
> While playing, I can switch the "Input mode" to
> change between "Stereo" and "PLII".

As I mentioned I have never heard of PLII prior to this, and my receiver doesn't have anything about that.

>> My receiver has options for THX, Dolby/DTS
>> Surround, Stereo, and Direct.

> PLII is (the successor of) Dolby Surround afaict.
> Since Dolby Surround and DTS Surround are two
> completely different things afaik, I am
> surprised that this is the same option...

The button actually has the Dolby logo and the letters DTS above the button, and the word "SURROUND" below the button.  I think that the way this receiver works is that you can select a mode, but if it gets a stream that is in a format it understands it will play it regardless of whether you have selected THX or Dolby/DTS.  However if you select Stereo or Direct, a relay clicks inside and I think the rear channels are completely disabled, possibly for those who have this receiver but only stereo speakers connected.

> I would be surprised if the file is THX but I
> don't know much about it, my receiver does not
> support it (too cheap).

I think you are correct but as I say it plays exactly the same whether THX or Dolby/DTS is selected (within the same program).

> (From a very quick look, THX is unrelated:
> "A common error is that THX is similar to
> Dolby Surround.")

Which is what makes me think that this receiver will let you select one or the other, but actually uses what it receives.

Keep in mind that all of this is with a S/PDIF (Toslink audio) connection; it might be different if the receiver had HDMI support, but it's not quite that new.

Thank you again and sorry for sending the wrong information the first time.

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