True HD + AC3 to DTS [Archive]

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MiniMinimal

26th February 2009, 12:56

ACrowley

26th February 2009, 13:10

Hello, i'm trying to convert True HD + AC3 to DTS.
But then i need "surcode encoder" it says.
When i'm using "eac3to"

Why?

Can't i just:

1) "true-HD + AC3" to .pcm
2) mux it into .ts container
3) downconvert it to dts with tsmuxer?

or do i loose quality then?
or shall i just get surcode?

whats the best?

No, you cant "downconvert" TrueHD to dts also not with tsmuxer.
You can extract the AC3 Core from TrueHd, because a BlurayTrueHD Tack (which is lossless) includes a seperate Dolby Digital 5.1 640 Kbps "Core"

You need the surcode dts encoder to reencode TrueHD to dts ,ofcourse.
eac3to decodes TrueHD to PCM (nearly lossless) and then encode the uncompressed PCM to dts.

Your Alternative is :
1 Get Surcode dts encoder and reencode the TrueHD to dts
2.Use the extracted AC3 5.1 640Kbps Core. Its "lossless" (ofcourse AC3 itself is a lossy Format)without any reencoding. I would prefer this Method instead of using Surcode Encoder.

MiniMinimal

27th February 2009, 00:23

why would u prefer Ac3 format?
ain't DTS on a better bitrate? or do surcode take the quality away when u reencode it? big thanx! for the answer by the way :)

Skelsgard

27th February 2009, 05:24

The AC3 640kbps core would be preferred for the sake of convenience as it would be a direct extraction from the TrueHD track, without the need to encode anything. It's faster and a lossless procedure, cause it´s already there.
DTS has a HIGHER bitrate, not BETTER. DTS and AC3 have different compression algorithms. DTS could be considered, in fact, less effective compression algorithm than AC3, as you can encode a Dolby track with 640kbps and not hear any difference with the original master, whereas you need to encode DTS at 1536kbps (2.4x higher bitrate) to get the same perceptual quality.
Encoding DTS at 768kbps is far more likely to give you a preceptual difference with the master.
If you were to compare an MP2 track (MPEG-1 layer 2) to and AAC track (MPEG-4 LC) you wouldn´t say that MP2 is better than AAC because it encodes at 224 kbps for a quality that you get with AAC at 128kbps, if you follow what I´m saying.
No, you would say that AAC is better (or more effective) because it provides the same perceptual quality with far less bitrate than MP2.

The usual statement you hear about DTS is that because ithas higher bitrate it´s better than AC3 and sounds better, or it has deeper bass and whatnot.
Well, the reality is that DTS and AC3 tracks in movies are often encoded from different masters, with different equalization, so they could never sound the same.
Trust me, if you encode the same master in AC3 640 and DTS 1536, you and 99% of the people in the world wouldn´t be able to tell the difference between both formats.
The other 1% is the people with perfect pitch perfect high notes hearing (and sadly and luckily i´m not one of them :) ).

I hope this clarifies a little.
Still, if you want to encode to DTS, what ACrowley told you is the way to go.

...eac3to decodes TrueHD to PCM (nearly lossless) and then encode the uncompressed PCM to dts.

Not "nearly lossless". Lossless.
If the encoded track is lossless, than the decoded output should be lossless, unless eac3to is not decoding TrueHD properly.
Maybe I missed something. Are there any bugs reported regarding libav and TrueHD decoding quality?

Later :cool:

Skelsgard

27th February 2009, 05:37

P.D. Surcode is in fact a crappy encoder, not in terms of the quality of the output DTS track, but in terms of encoding features.
It can only output 5.1 48kHz DTS tracks at 1536 or 768kbps or 44.1kHz at 1141kbps.
No other configuration, i.e. 2.0, 3.1, 4.0, DTS-ES, etc.
And there are no free encoders out there. All are commercial: Surcode DTS DVD Pro, DTS Pro Series Encoder, up to DTS-HD Master Audio.

For AC3 there´s Aften, which is a high speed high quality feature-rich free encoder. Absolutely recommended.

Later :cool:

MiniMinimal

27th February 2009, 10:43

This was the answer i was looking for thanx mate :)
Now i understand all clearly!

MiniMinimal

27th February 2009, 11:24

Just one more Q then :)
Wouldn't the True-HD part theoretical be a better master?
(it's a new format, and the "AC3 part" could be from a older DVD version of the movie?)

Well, the reality is that DTS and AC3 tracks in movies are often encoded from different masters, with different equalization, so they could never sound the same.

Then if i reencode the True-HD track to .AC3? (lossless)
And then it should be two different .AC3 tracks?

One that i extracted from the True-HD+AC3
And one that reencoded from the True-HD+AC3

And that is equal to two different masters?

Am i right?

ps. i know that i'm a little bit goof now but i hope that you guy's doesn't get bored of me ds.

:thanks:

Audionut

27th February 2009, 15:57

WTF are you guys saying uncompressed PCM is "nearly lossless" and ac3 is lossless!!!!

TrueHD is lossless. It was created with a 640kbps core to make it backwards compatible with "older" hardware. The core by itself is not lossless.

In terms of quality when using a compliant TrueHD decoder,

1. Keep TrueHD
2. Encode to PCM/WAV
3. Encode to DTS 1536
4. Extract AC3 core.

tebasuna51

27th February 2009, 17:01

In terms of quality:

10: Keep TrueHD, Decode to PCM/WAV, encode to FLAC
8: Encode to DTS 1536
7: Extract AC3 core 640 -> 448
6: Encode to AAC 320
5: Encode to DTS 768
...

In terms of size:

9: Encode to AAC 320
7: Extract AC3 core 640 -> 448
6: Encode to DTS 768
5: Encode to DTS 1536
3: encode to FLAC
2: Keep TrueHD
1: Decode to PCM/WAV,

ACrowley

27th February 2009, 19:53

@skelsgard

No, youre not missing anything :) ofcourse TrueHD/DTSHD decoding to PCM/Raw is losless. And when its bit prefect its lossless. And so far i know eac3to decodes TrueHD/DTSHD bitperfect

@Miniminimal
Ah, i see why youre talking about TSMuxer and DTS downconverting :)
The Option in TSmuxer Downconvert to dts is for DTS-HD. Because DTS-HD(lossles when its MA Profile) has a dts 1536kbps 5.1 core. In the same Way as TrueHD has a AC3 core.
The TSmuxer Option means that you can extract the DTS Core from DTS HD

Skelsgard

27th February 2009, 22:21

Just one more Q then :)
Wouldn't the True-HD part theoretical be a better master?
(it's a new format, and the "AC3 part" could be from a older DVD version of the movie?)
The 640kbps AC3 core is generated on the encoding of a TrueHD+AC3 track. Is not an "encode to TrueHD and encode to AC3 (or retrieve an old AC3), and then mixed them together" kinda process.
Being TrueHD lossless, it's a BITPERFECT COPY of the original master, not a better master but the same.
And being the AC3 core encoded with a compliant AC3 encoder (the one that encodes to TrueHD+AC3), then theoretically if you encode your own AC3 from the TrueHD track (with a compliant encoder and using the same settings) your resulting AC3 should be exactly the same as the AC3 core.

Then if i reencode the True-HD track to .AC3? (lossless)

WTF are you guys saying uncompressed PCM is "nearly lossless" and ac3 is lossless!!!!

I did not say that AC3 was lossless but the process of extraction of the AC3 core is lossless since there is no decoding-reencoding of the core when you extract it. It's basically a ripping.
And MiniMinimal didn´t say it was lossless but he asked if it was (see the question mark?)
Maybe ACrowley just had a millisecond-long mental typo but he does know what he is talinkg about.

Later

MiniMinimal

27th February 2009, 23:40

@Miniminimal
Ah, i see why youre talking about TSMuxer and DTS downconverting :)
The Option in TSmuxer Downconvert to dts is for DTS-HD. Because DTS-HD(lossles when its MA Profile) has a dts 1536kbps 5.1 core. In the same Way as TrueHD has a AC3 core.
The TSmuxer Option means that you can extract the DTS Core from DTS HD

Ok, i see! That was the thing i was talking about when i mentioned Tsmuxer :) I was confused about if it was PCM or DTS-HD track. sorry my mistake.

why doesn't people use flac? if it is a good alternative? i have never seen people using it on a movie?

Inspector.Gadget

28th February 2009, 05:11

Ok, i see! That was the thing i was talking about when i mentioned Tsmuxer :) I was confused about if it was PCM or DTS-HD track. sorry my mistake.

why doesn't people use flac? if it is a good alternative? i have never seen people using it on a movie?

Well, neither Blu-ray or HD-DVD specs allow for FLAC audio. In terms of back-ups for your own use, FLAC is fine but realistically most people can't tell the difference between efficient lossy codecs and lossless codecs. If you're asking why "the scene" usually doesn't use FLAC

1)they follow a somewhat arbitrary set of rules;
2)the scene doesn't focus on quality alone;
3)because of Rule 6, I don't think many scene encoders hang out to ask questions on Doom9 :p

MiniMinimal

28th February 2009, 10:21

I have never seen no one here mentioned *.flac before.
VLC does not support it? I always check with VLC when i wan't see if something has a good support. And it can't handle flac. strange?
:confused:

Skelsgard

28th February 2009, 13:29

VLC does support FLAC.
FLAC is a widely supported codec as PC players and audio filters go, but not in standalone players, like Inspector.Gadget said.
So basically, if you intend to encode the audio to play your movie in your PC, FLAC is a valid option. If you intend it for a SAP Blu-Ray or HD-DVD, FLAC won't be recognized by them.