[mythtv-users] anyone have AC3/DTS passthrough working with revo 1600?

[Jean-Yves Avenard]

Hi

On 9 June 2010 10:51, Brian J. Murrell <brian at interlinx.bc.ca> wrote:
> I might be showing my ignorance here (which abounds in this whole AV
> arena, so not surprising) but then how does my TV play the audio from
> (clearQAM) digital cable channels, which can either be heard on the TV's
> speakers or on the amp's speakers with the amp registering the input as
> Dolby Digital?

because it only does so for 2 channels.

>
> Further, how can my TV play a video file that mplayer reports as having
> a digital sound track:
>
> Opening audio decoder: [liba52] AC3 decoding with liba52
> dec_audio: Allocating 3840 bytes for input buffer.
> dec_audio: Allocating 6144 + 65536 = 71680 bytes for output buffer.
> Using SSE optimized IMDCT transform
> AC3: 5.1 (3f+2r+lfe)  48000 Hz  448.0 kbit/s
> A52 flags before a52_frame: 0x2A
> A52 flags after a52_frame: 0xA
> Using MMX optimized resampler
> AUDIO: 48000 Hz, 2 ch, s16le, 448.0 kbit/29.17% (ratio: 56000->192000)
> Selected audio codec: [a52] afm: liba52 (AC3-liba52)

But who does the decoding here ?

and you're outputting 2 channels audio in your example

If you configure mplayer to output passthrough, you'll find yourself
in the same situation as with myth

>
> via it's (the TV's) DLNA feature without an AC3[/DTS] decoder?  IOW, the
> TV plays this file directly, from myth's UPnP/DLNA service, not decoded
> and displayed by myth.
>
>> When you're doing a connection like:
>> PC -> TV -> Amp
>>
>> in my experience, the TV only passthrough stereo PCM ; including over
>> their digital out connector nothing else. At least that's what my Sony
>> and Samsung TVs do.
>
> Interestingly, my TV is Samsung Series 5 PN50C540
> (http://www.samsung.com/us/consumer/tv-video/televisions/plasma-tv/PN50C540G3FXZA/index.idx?pagetype=prd_detail)
>
> Also, my TV has a selector for its' SPDIF out (which goes to my amp of
> course) on it to specify whether to output PCM or Dolby Digital, and the
> DD option only appears to be selectable (i.e. not greyed out) when the
> input is AC3 (and perhaps DTS, which I have not entered into this mix
> yet) such as from clearQAM cable or Myth.  And when I select Dolby
> Digital, the amp does register the input has being DD.  In the case of a
> clearQAM cable signal, everything is fine.  I can hear the sound, in DD
> on the amp.  In the Myth case, playing the file from which the above
> mplayer output comes, the TV let's me select DD as the SPDIF format, but
> the Amp doesn't seem to receive that.  Additionally, when the TV is set
> to output on it's own speakers, it's just silent.
>

you can hear it when it's 2 channels ...

>> If you want AC3/DTS passthrough, you have to connect your system like:
>> PC -> Amp -> TV
>
> My amp doesn't handle HDMI.  :-(

use the SPDIF output then from the PC directly instead of going through your TV