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Old 26th March 2011, 18:23   #1  |  Link
billsantos
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confirming lossy DTS core from lossless?

I have been using eac3to to extract what I thought were lossless tracks from a DTS Master Audio 7.1 ch track. I have the output set to wavs and I do, in fact, get 8 mono wave files, all 24 bit, 48 Khz with 1152 kbps bit rate. Now when I do this same process with -core at the end, I get 6 audio channels of wave files, but in the file specs, they are also listed as 24 bit, 48 Khz, 1152 kbps. When I listen to the audio tracks, they sound the same fidelity wise, so I am wondering if I am really getting lossy or lossless depending on what command is used? How would I check for sure? thanks.
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Old 26th March 2011, 22:46   #2  |  Link
billsantos
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I at least managed to find some confirmation. I opened the BD in Nero and saw that four audio tracks could be selected. The default was...

1) DTS, 2 channel 4000- 5000 kbps (varied as movie played) from DTS Master Audio 8 channels stream

and then when I selected 2), I got Dolby Digital, 2 channels, 192 kbps

3) and 4) were just the DD channels in other languages.

Now I have some questions:

1) If I listen and switch from 1) to 2), I hear no difference in fidelity. Shouldn't I hear something especially if the kbps is dropping that much?

2) Eac3to must be saving to a default of 24 bit, 48 Khz, 1152 kbps no matter what since I am specifying wavs as output. My guess is that the actual files are as above and retain those properties even though saved as default (?)

3) I am not very impressed with these DTS Master Audio tracks, if this is in fact what I am hearing. I have an old analog VHS of the same thing I have on BD and the audio is much better on the high end (treble) of the VHS. If these DTS Master Audio tracks are supposed to be bit-to-bit copies from the original master tapes, then there must be some sort of processing going on before it reaches the BD. My guess is some sort of noise filtering to clean up the tracks (perhaps DD even though these are the DTS Master Audio tracks), but the result is quite lossy on the top end. If so, I'm sorry to see this type of processing going on as the high end is compromised quite a bit.

Anyone else notice this, or just me? BD based movies sound "cleaner", but not necessarily better fidelity. Just to see if I could reach the analog equivalent of the top end of the VHS, I used some software EQ. It took two +20 db 10 Khz high pass stacked filters to start reaching the equivalent of the analog fidelity!
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Old 27th March 2011, 12:33   #3  |  Link
tebasuna51
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1) Put the eac3to log to know your original tracks

2) If you extract from -core you obtain lossy output.

3) To listen the differences between lossless and a good lossy encode you need a good audio equipment and good ears.
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Old 27th March 2011, 14:44   #4  |  Link
billsantos
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Quote:
Originally Posted by tebasuna51 View Post
1) Put the eac3to log to know your original tracks
Ok, here are the logs:

eac3to v3.24
command line: c:\eac3to\eac3to.exe C:\test\00006.m2ts 2: C:\test\test.wavs
------------------------------------------------------------------------------
M2TS, 1 video track, 4 audio tracks, 4 subtitle tracks, 0:09:58, 24p /1.001
1: VC-1, 1080p24 /1.001 (16:9)
2: DTS Master Audio, 7.1 channels, 24 bits, 48kHz
(core: DTS, 5.1 channels, 24 bits, 768kbps, 48kHz)
3: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
4: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
5: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
6: Subtitle (PGS)
7: Subtitle (PGS)
8: Subtitle (PGS)
9: Subtitle (PGS)
[a02] Extracting audio track number 2...
[a02] Decoding with ArcSoft DTS Decoder...
[a02] Writing WAVs...
[a02] Creating file "C:\test\test.R.wav"...
[a02] Creating file "C:\test\test.BL.wav"...
[a02] Creating file "C:\test\test.LFE.wav"...
[a02] Creating file "C:\test\test.SR.wav"...
[a02] Creating file "C:\test\test.L.wav"...
[a02] Creating file "C:\test\test.C.wav"...
[a02] Creating file "C:\test\test.BR.wav"...
[a02] Creating file "C:\test\test.SL.wav"...
[a02] The original audio track has a constant bit depth of 24 bits.
Video track 1 contains 14331 frames.
eac3to processing took 1 minute, 12 seconds.
Done.

This was for the supposed 8 channel lossless extraction from the DTS Master Audio track. Now, the core command and result:

eac3to v3.24
command line: c:\eac3to\eac3to.exe C:\test\00006.m2ts 2: C:\test\testcore.wavs -core
------------------------------------------------------------------------------
M2TS, 1 video track, 4 audio tracks, 4 subtitle tracks, 0:09:58, 24p /1.001
1: VC-1, 1080p24 /1.001 (16:9)
2: DTS Master Audio, 7.1 channels, 24 bits, 48kHz
(core: DTS, 5.1 channels, 24 bits, 768kbps, 48kHz)
3: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
4: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
5: AC3, 2.0 channels, 192kbps, 48kHz, dialnorm: -27dB
6: Subtitle (PGS)
7: Subtitle (PGS)
8: Subtitle (PGS)
9: Subtitle (PGS)
[a02] Extracting audio track number 2...
[a02] Extracting DTS core...
[a02] Decoding with ArcSoft DTS Decoder...
[a02] Writing WAVs...
[a02] Creating file "C:\test\testcore.L.wav"...
[a02] Creating file "C:\test\testcore.SR.wav"...
[a02] Creating file "C:\test\testcore.C.wav"...
[a02] Creating file "C:\test\testcore.R.wav"...
[a02] Creating file "C:\test\testcore.SL.wav"...
[a02] Creating file "C:\test\testcore.LFE.wav"...
[a02] The original audio track has a constant bit depth of 24 bits.
Video track 1 contains 14331 frames.
eac3to processing took 2 minutes, 3 seconds.
Done.

Quote:
2) If you extract from -core you obtain lossy output.
Doing it as above and then listening on premium headphones and seeing spectrum analysis, I can't tell a difference between the core and the lossless.

Quote:
3) To listen the differences between lossless and a good lossy encode you need a good audio equipment and good ears.
I also did a Dolby Digital extraction of track 3:. Same thing, no difference detected in audio. As I said before though, I hear a BIG difference in the top end when I play the original VHS. The VHS sounds much better and fuller as the expense of slightly more noise.

I must conclude therefore that there must be some sort of processing going on before the tracks are laid down onto the BD, and such processing must not have occurred when the VHS tapes were made. Someone is another forum did mention that VHS HiFi might have been responsible, but I wouldn't think there'd be THAT much difference in the top end.

Last edited by billsantos; 27th March 2011 at 14:46.
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