thks to Kujibo's trick, I tested DTS & AC3 furthermore:
Here is what I did:
I took Castanet 2.0 44.1Khz I splitted it in two channels using Audacity then I resampled each channels to 48Khz, I rejoined the channels to have a lossless Castanet 2.0 48Khz as a reference.
Then, as SurCode wants 6 channels as input, I copied the right & left channels 3 times & I encoded to DTS 1536 & 768Kbps (default settings) creating two fake Castanet 5.1 48Khz files, with duplicated channels.
Then, I remuxed the two DTS file in MKA with MKVMerge & decoded it to wav using EAC3to, I deleted he fake duplicated channels with Audacity (keeping only front left & front right) & I encoded to flac & replaygained the result with F2K.
see how complicated it is to test DTS ... (with the final files, I didn't have the loudness problem I had previously)
I ended with 3 files:
Castanets Lossless WAV 2.0 48Khz.flac
Castanets Lossy DTS (SurCode V1.0.21) 307Kbps 2.0 48Khz.flac which AFAIK is equivalent to DTS 5.1 0768Kbps
Castanets Lossy DTS (SurCode V1.0.21) 614Kbps 2.0 48Khz.flac which AFAIK is equivalent to DTS 5.1 1538Kbps
Then I tried to ABX it,
I don't know if my methodology is really valid but I don't know how to do it better ...
DTS (SurCode V1.0.21) 614Kbps 2.0 48Khz Vs. WAV 2.0 48Khz:
ABX failed.
DTS (SurCode V1.0.21) 307Kbps 2.0 48Khz Vs. WAV 2.0 48Khz:
ABX 100% sucess
foo_abx 1.3.3 report
foobar2000 v0.9.6.3
2009/03/01 02:57:07
File A: C:\Documents and Settings\Sauvage\Bureau\Castanets Lossless WAV 2.0 48Khz.flac
File B: C:\Documents and Settings\Sauvage\Bureau\Castanets Lossy DTS 307Kbps 2.0 48Khz.flac
02:57:07 : Test started.
02:57:48 : 01/01 50.0%
02:58:31 : 02/02 25.0%
02:59:08 : 03/03 12.5%
03:01:43 : 04/04 6.3%
03:02:41 : 05/05 3.1%
03:04:01 : 06/06 1.6%
03:05:18 : 07/07 0.8%
03:07:32 : 08/08 0.4%
03:07:39 : Test finished.
----------
Total: 8/8 (0.4%)
Conclusion:
On castanets killer sample & with SurCode V1.0.21
DTS 5.1 1538Kbps is most likely transparent
DTS 5.1 0768Kbps is not transparent
Now I wanted to test DTS 5.1 768Kbps Vs. AC3 640Kbps to know which one was better, I took the best AC3 encoder I previously quickly tested & encoded my 2.0 48Khz wav to 2.0 256Kbps 48Khz AC3.
& first I tried to ABX the AC3 vs the original:
AC3 (Soft Encode V1.0 Build 19) 256Kbps 2.0 48Khz Vs. WAV 2.0 48Khz:
ABX 100% sucess
foo_abx 1.3.3 report
foobar2000 v0.9.6.3
2009/03/01 03:46:27
File A: C:\Documents and Settings\Sauvage\Bureau\Castanets Lossless WAV 2.0 48Khz.flac
File B: C:\Documents and Settings\Sauvage\Bureau\Castanets Lossy AC3 (Soft Encode V1.0 Build 19) 256Kbps 2.0 48Khz.flac
03:46:27 : Test started.
03:47:37 : 01/01 50.0%
03:48:26 : 02/02 25.0%
03:49:32 : 03/03 12.5%
03:51:31 : 04/04 6.3%
03:52:34 : 05/05 3.1%
03:53:51 : 06/06 1.6%
03:54:58 : 07/07 0.8%
03:56:16 : 08/08 0.4%
03:56:21 : Test finished.
----------
Total: 8/8 (0.4%)
Unlike what I previously said, with a regular ABX test, AC3 from Soft Encode V1.0 Build 19 is ABXable even at 256Kbps & quality is not OK. (It is just better than worst settings which are awfull)
Then I compared AC3 (Soft Encode V1.0 Build 19) 256Kbps 2.0 48Khz Vs. DTS (SurCode V1.0.21) 307Kbps 2.0 48Khz:
I can ABX a difference between both but I cannot really declare which is best, both are bad (really bad) but not terribly awfull (not unlistenable & not instantly ABXable)
for me
DTS preserve the fluidity better but lose the sharpness of the attacks.
AC3 sounds flatter but the attacks is better than DTS (maybe because being flat it sounds slightly slower).
both sound like "a metallic spoon rubbed against a grid", with DTS the spoon is rubbed faster but softer & with AC3 the spoon is rubbed slower but harder. (I don't know how to tell it better)
On this sample that is said to be a killer sample for transform codecs, AC3 being a transform codec & DTS being a subband codec, doesn't help DTS much.
so far personnaly I think I still favor AC3 256Kbps over DTS 307Kbps as I think I favor the "slow" effect artefact vs. the "soft" effect artefact ... if you get what I mean.
for me the sound seems more stable with AC3 256Kbps, DTS 307Kbps seems to sound slightly blurry. But it's really hard to chose between artefacts. To be fully honest I must say that I am undecided yet.
It's a matter of taste here & I may change my mind here as I am curently still ABXing them. Maybe in a week when I get used to the artefacts, I could tell which one I really favor.
I am currently in full paradox here as I think DTS seems to sound more naturals, but it softens the attack which modify the agressivity of the sample. AC3 is un-natural (slightly metallic) but doesn't soften the attacks.
It is the same kind of artefacts than between musepack & MP3 at mid/low bitrate (96-128Kbps), none is transparent at all, but it sounds different. It's like as if transform codecs were metallising the sound while suband codecs were ereasing sounds. At first try, what you don't hear sounds more natural than what hear as robotic, but I don't know why but I favor hearing artefact than not hearing data. That's why I never liked musepack personnaly, as I listen to loud music (metal) I don't like its tendancy to soften the rhythmic.
finally I don't consider AC3 5.1 640Kbps & DTS 5.1 768Kbps transparent on music anymore.
the quality of both is bad & roughtly equivalent, but it is acceptable for speech & background music.
DTS 5.1 1538Kbps is a good source for transcoding & I consider it always far superior to AC3 640Kbps ... there is no competition here.
For me, the claim that AC3 5.1 640Kbps is as transparent as DTS 5.1 1538Kbps is a commercial lie. NO doubt here.
people transcoding DTS to AC3 are nuts (specially DTS 768Kbps to AC3 & specially with free AC3 encoders which are terrible)... they should keep the original or use Nero AAC-Vorbis at 320Kps IMHO
Hope it helped. See ya.