[DTS-HD MA/TrueHD/LPCM to FLAC] Lossless?

[jfromeo]

Good evening.

I'm in the process of dumping and demuxing my BluRay collection and I'd like to ask some questions before doing something wrong (aka not reversible ).

I'm dumping and demuxing my BD collection into my PC HDD, which I intend to use as a HTPC later. I see all the codecs/containers listed above are lossless, that means the resultant audio file will be identical bit-per-bit to its original waveform, right?

That said, I see FLAC allows a greater compression than the rest (especially LPCM) saving quite a lot of space for the same quality. So my intention was to go with FLAC for all my lossless audio tracks, and the questions are:

1) I'm using eac3to, so, would I need a "special" (private/propietary) codec for transcoding the DTS-HD MA/TrueHD/LPCM tracks into FLAC? If so, which one?

2) Is the process reversible? I mean, would I be able to transcode the FLAC audio file to its "original" codec (DTS-HD MA/TrueHD/LPCM) if needed?

3) I'll be using my PC as playback (a so-called HTPC), but I'd be sending the signal to an Onkyo external receiver (TX-NR5007) through HDMI 1.3a. Would it give a "better" sound quality by decoding a DTS-HD MA/TrueHD/LPCM track than a FLAC, or would the sound be absolutely the same?

Thanks everyone.

[Snowknight26]

1. Only for DTS-HD MA. Run eac3to without any arguments.. it'll tell you what you need.
2. Yes (for LPCM at least). The other two require you to spend some serious cash.
3. Lossless is lossless. All of them have to be identical when decoded. Do note though that they're all decoded to LPCM when being sent over HDMI (unless you bitstream).

[jfromeo]

Thanks so much Snownight.

I guess I'll maintain the audio tracks in their respective original codecs then, I'll always have time to convert them to FLAC when needed.

But this lead me to a another side question. I'm using latest eac3to (v3.4) along with the GUI HD-DVD/BDStreamExtractor (v0.7), and when I check a TrueHD audio track, and expand the "Extract as" field, I don't get any *.trueHD extension (or similar), only the AC3 core (among others). Do I need to have installed a propietary codec for demuxing TrueHD tracks? I thought there was no need of codec for demuxing, only for encoding/decoding tasks.

I have no problem with the rest of typical BD audio encoded tracks:

AC3 (*.AC3)


DTS (*.DTS)


DTS-HD MA (*.DTSHD)


LPCM (*.RAW)

But with TrueHD, this is what I get:

[TinTime]

eac3to certainly allows you to demux TrueHD tracks but it looks like that GUI doesn't. You could try another front end, or give CLI a go.

In fact it looks like THD isn't working for this GUI - see here - but will be added in the future.

[tebasuna51]

A TrueHD/AC3 track have a TrueHD audio and an AC3 audio together.
You can select Extract as: AC3
and write in +Options:
4:"R:\yourpath\yourname.thd"

Then you extract both audios to independent files.

eac3to can join after the two files, or , if you want extract the full thd+ac3 for BD authoring, put in +Options:
4:"R:\yourpath\yourname.thd+ac3"

[jfromeo]

Thanks both, I'll wait for another revision of the GUI, as I have tried ClownDB and, although it is able to demux TrueHD tracks, it lacks of DTS-HD demuxing lol

[Snowknight26]

You could always use eac3to without a GUI.

[Blue_MiSfit]

Yes, this works very well and only requires a few minutes of head scractching

Here's a sample code, assuming your BD-ROM is your F:\ drive, the playlist in question is #1, track 2 is your 1080p video, and track 3 is your DTS-MA track.

eac3to f: 1) 2:Video.mkv 3:Audio.dtsma

I would encourage you to do some subjective listening tests of a lossless audio track, and a very good lossy encode, like Nero's AAC encoder on default settings. You will experience a MASSIVE bitrate reduction (i.e. 6mbps for 5.1ch PCM to ~600kbps for 5.1ch AAC), and I think you would be EXTREMELY hard pressed to tell any difference.

That being said, if you're sold on lossless, and have enough storage, more power to you Just a suggestion.

As far as decoding DTS-MA on the PC, you basically have to buy ArcSoft's TMT software. You can't buy the newest version, you have to find a copy of the older version, since newer versions restrict access to its DLLs by third party apps (eac3to). It's about $100 if you can find it somewhere online.

TrueHD can be decoded by libavcodec (in eac3to), and PCM is PCM

~MiSfit

[jfromeo]

Thanks Misfit!

Yeah, I can't hardly tell apart a FLAC from a V0 audio file (I can from a V2/128kbps or lower though with the right equipment), so I guess there would be no difference between the lossless track and a good lossy encode to my ears. But it's more a "philosophy" to maintain the tracks as they were originally encoded, untouched, for each BluRay. Even a LPCM (in raw), although I know encoding it to FLAC for example would make no impact in the waveform, but would reduce it to almost 1/3 its original size.

I'll give the CLI a try. I can always demux every track but the TrueHD one with a GUI, and the TrueHD tracks (which are the ones that are giving me problems) with the CLI right?

[jfromeo]

The HD-DVD/BDSE GUI included in latest MeGUI supports demuxing TrueHD tracks

But I have a doubt, I am given two options, THD and THD+AC3 Core. The THD one already includes the AC3 core right? I mean, the resultant file is already the lossless track right? No need to extract the AC3 core too and "embed" it to the THD track.

[nurbs]

No, the core is separate from the THD track. They don't depend on each other. You don't need the AC3 track if you just want the lossless track.

[jfromeo]

Ok thanks. I was asking it as I demuxed a 2h movie TrueHD track and its size was ~1.3GB (and ~600MB the AC3 core), while on DTS-HD a 2h movie rounds ~2GB. Both were 24-bit, 98Khz, 5.1 channels audio (VBR obviously). So I was surprised the THD+AC3 weighed about the same as the DTS-HD track.

[rahzel]

DTS-HD MA includes a core audio track so no special extension is required. To demux TrueHD with core AC3, you must use the extension "example.thd+ac3". Of course if you simply just want the core audio, just use the .thd extension.

[jfromeo]

Originally Posted by rahzel

Of course if you simply just want the core audio, just use the .thd extension.

Wouldn't it be .ac3 for the core, .thd for the lossless track and .thd+ac3 for both (pretty useless if you can decode the thd track for me)?

[tebasuna51]

Yes, is a Rahzel's typo, I suppose.

[rahzel]

Oops, what I meant to say was, if you just want the HD audio, you can use the .thd extension (or .ac3 for core).

[jfromeo]

Oh thanks, I almost suffered from a heart attack, as I had already demuxed all my dumps and deleted the original folders