[mythtv] Audio-upmixing questions regarding #5900

foo bar foobum at gmail.com
Mon Nov 17 01:24:56 UTC 2008


2008/11/16 Yeechang Lee <ylee at pobox.com>:
> I've patched my 0.21-fixes setup with #5900, and am pleased that now
> 5.1 audio works when timestretching, as well as fixing some other
> issues.
>
> Three questions:
>
> * Is 5.1 audio always upmixed, or is it passed through by default
>  unless there's timeshifting?

5.1 audio is never upmixed (no need). It will be passed thru
unmolested unless there's timeshifting.

> * If the answer to the previous question is "Passed through," does
>  upmixing automatically stop and the frontend revert to the native
>  audio track if a 5.1 recording's timestretch is returned to 1.0X?

As above, the upmixer would never have been turned on. However, (as
before) the AC-3 will still be decoded and then re-encoded if we
timestretch and then revert to 1.0x. This makes very little
difference.

> * What advantages/disadvantages, if any, are there to upmixing non-5.1
>  audio to 5.1?

Advantages: Sounds nice
Disadvantages: The upmix/encode to AC-3 costs a few cycles


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