www.makemkv.com

liquidskin76 wrote:Hey Mike,

You said MakeMKV just copies the TrueHD track as is. I'll run another test using a MakeMKV mkv containing ONLY the TrueHD track and see if i get TrueHD over HDMI and AC3 over optical. It maybe that i'm mistaken, and the TrueHD track produced by MakeMKV does keep the AC3 core.

I'm sure i've done this test before however i think i'm starting to think i'm losing my mind!

Thanks

Channel Extensions, Downmixing, and Dolby TrueHD
One channel extension technique is the method by which MLP Lossless, Dolby TrueHD, and MPEG-2 LII deliver compatible downmixes for soundtracks with expanded channels. In these codecs, a 7.1-channel soundtrack is first downmixed to create a 5.1 mix...

If a listener selects a 5.1 presentation, the decoder reconstructs it from the
two-channel downmix plus the 3.1-channel extension A substream by means of rematrixing.

An A/V receiver with Dolby Digital decoding that has only a coaxial or optical digital audio input needs only a Blu-ray Disc player with a Dolby Digital Compatible Output that provides a compatible Dolby Digital bitstream from its internal mixer.

Due to the substream structure of Dolby TrueHD, a single Dolby TrueHD program can be used to deliver a two-, six-, or eight-channel presentation, each with precise control over the presentation as defined by the content producer. This means that an HD player needs to decode only the number of channels it can output, thus enabling more economical DSP decoder designs.

It should be noted that it is also possible for the two- and 5.1-channel presentations to be carried independently if it is important to avoid downmixing due to artistic reasons. In this case, however, the bit rate will increase due to the carriage of additional channels.

mrbass wrote:AC3 your are "seeing" is simply metadata telling it to downmix within the TrueHD stream. There is no AC3 core like you say although technically an AC3 track could be "carried independently" (NOT WITHIN TRUEHD stream). There simply isn't a need as all TrueHD receivers are capable of downmixing to 5.1 or 2.1. Although your saying you disabled TRUEHD decoding it's still just reading the metadata to downmix it. Just like on HD media player if you disable digital output and choose stereo it is STILL reading the digital DTS audio and downmixing it to stereo. Probably bad choice of terms being used by the programs.

Here's a few snippets from the technical PDF paper
http://www.dolby.com/uploadedFiles/Asse ... _Final.pdf

Channel Extensions, Downmixing, and Dolby TrueHD
One channel extension technique is the method by which MLP Lossless, Dolby TrueHD, and MPEG-2 LII deliver compatible downmixes for soundtracks with expanded channels. In these codecs, a 7.1-channel soundtrack is first downmixed to create a 5.1 mix...

If a listener selects a 5.1 presentation, the decoder reconstructs it from the
two-channel downmix plus the 3.1-channel extension A substream by means of rematrixing.

An A/V receiver with Dolby Digital decoding that has only a coaxial or optical digital audio input needs only a Blu-ray Disc player with a Dolby Digital Compatible Output that provides a compatible Dolby Digital bitstream from its internal mixer.

Due to the substream structure of Dolby TrueHD, a single Dolby TrueHD program can be used to deliver a two-, six-, or eight-channel presentation, each with precise control over the presentation as defined by the content producer. This means that an HD player needs to decode only the number of channels it can output, thus enabling more economical DSP decoder designs.

It should be noted that it is also possible for the two- and 5.1-channel presentations to be carried independently if it is important to avoid downmixing due to artistic reasons. In this case, however, the bit rate will increase due to the carriage of additional channels.

liquidskin76 wrote: Have just been looking through the official TrueHD spec, before you posted. I understand now... so no separate ac3 file, just metadata telling the player/software how to downconvert.

Ok, so let me revise my original request... can MakeMKV keep this metadata so a software player can downconvert a truehd track to ac3!!??

robinsj wrote:I am really unsure what you are requesting here, because I have the exact setup you describe. I have 2 HTPCS both running XBMC. One uses hdmi out to a receiver that fully supports DTS-HD and TrueHD. The other is hooked up to a receiver via Optical/Toslink. The one with HDMI to the receiver plays everything with the DTS-HD and TrueHD lighting up the receiver. The other plays everything just fine too, and doesn't just play 2 channel audio.

The one that is connected via HDMI, I have setup in ffdshow audio configuration, in the output section, I have everything checked under the Pass-through (S/PDIF, HDMI) section. Then the other one with just the optical hookup, I only selected everything but truehd, and dts-hd. Everything plays back fine in 5.1 audio, and I don't keep two audio tracks in the truehd ones, just the truehd track.

What problem are you having?