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Old 31st May 2010, 15:28   #10041  |  Link
Majin3
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Hello, since this is my first time dealing with DTS, I wanted to ask some questions here before doing anything wrong...
eac3to reports that my Blu-ray has "LPCM 16 bit 5.1", "DTS Master Audio 16 bit 5.1" and "LPCM 16 bit 2.0" audio tracks.
I want to extract the best quality one, but I'm a bit confused since eac3to reports that the DTS MA track is 16bit (which should decompressed be 1:1 to the first LPCM one, shouldn't it?) while its DTS core is 24bit (MediaInfo says the same).
Can that be correct? Shouldn't the DTS MA also be 24 bit or the DTS core 16 bit?
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Old 31st May 2010, 17:04   #10042  |  Link
nurbs
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DTS tacks don't really have a fixed bitdepth, lossy audio codecs don't in general.
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Old 31st May 2010, 17:17   #10043  |  Link
Majin3
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Ah, I see.
So the core is of varibale bit depth and the "Master Audio" extension patches it to 16 bit? Then I guess I'll just go with the LPCM track, thanks.
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Old 31st May 2010, 21:56   #10044  |  Link
madshi
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Quote:
Originally Posted by Abradoks View Post
Here they are.
SNR:
out.10N.nero.L.wav 27.386 dB
out.10N.libav.L.wav 27.411 dB
out.10S.nero.L.wav 5.5173 dB
out.10S.libav.L.wav 27.398 dB
tartak wrote on another forum, that with nero decoder DRC is only partially ignored: volume increasing still applies, while attenuation is ignored.
Argh, what I said earlier was wrong, I haven't been able to fix yet, unfortunately...

Quote:
Originally Posted by TinTime View Post
I've found a peculiarity when reducing the bit depth of a file. I've got a sample here to reproduce the problem (if it is a problem).
I'd say this is probably only a cosmetic issue, but I'll look into it.

Quote:
Originally Posted by iSeries View Post
Now the question! If I just put in the -down16 command will eac3to behave in the same way when it comes to 24 bit padded audio tracks and just remove the padding in a 2nd pass? Or does it blindly dither down to 16 bit without checking?
What is the source you will be using for -down16? Was the source created with eac3to? If so, if it's really only 16bit, then eac3to should already have saved it as 16bit, so if you use -down16, nothing will happen.

If your source claims to be 24bit, and if you use -down16, then eac3to will apply dithering - even if it's only really 16bit. The reason for that is that eac3to doesn't know which bitdepth the source has until processing is complete. You surely don't want eac3to to scan the whole file first, everytime, before starting processing, do you?
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Old 31st May 2010, 22:07   #10045  |  Link
madshi
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eac3to v3.19 released

http://madshi.net/eac3to.zip

Code:
* added support for 3D Blu-Rays (playlists, detection & demuxing)
Just a quick addition of 3D support. For playlist browsing it looks like this:

Code:
D:\BDMV\PLAYLIST>eac3to 00001.mpls
1) 00001.mpls, 00001.m2ts, 0:00:09
   - h264/AVC  (left eye), 1080p24 /1.001 (16:9)
   - h264/AVC (right eye), 1080p24 /1.001 (16:9)
   - DTS, English, multi-channel, 48kHz
For demuxing it looks like this:

Code:
M2TS, 2 video tracks, 1 audio track, 0:00:09, 24p /1.001
1: h264/AVC  (left eye), 1080p24 /1.001 (16:9)
2: h264/AVC (right eye), 1080p24 /1.001 (16:9)
3: DTS, English, 5.1 channels, 16 bits, 1509kbps, 48kHz
a03 Extracting audio track number 3...
v01 Extracting video track number 1...
v01 Extracting video track number 1...
a03 Patching bitdepth to 24 bits...
v01 Creating file "c:\desktop\test - 2 - h264 (right eye), 1080p24.h264"...
v01 Creating file "c:\desktop\test - 1 - h264 (left eye), 1080p24.h264"...
a03 Creating file "c:\desktop\test - 3 - DTS, English, 5.1 channels, 16 bits, 15
09kbps, 48kHz.dts"...
Video track 1 contains 211 frames.
Video track 2 contains 211 frames.
eac3to processing took 2 seconds.
Done.
Enjoy!

(Before anybody asks: The "left eye" stream is a normal h264 stream, which every h264 decoder supports. The "right eye" stream is a special h264 extension stream which current h264 PC decoders don't understand.)
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Old 31st May 2010, 22:55   #10046  |  Link
iSeries
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"If your source claims to be 24bit, and if you use -down16, then eac3to will apply dithering - even if it's only really 16bit."

So, I'll get better quality on padded sources if I first demux/convert to .wav? That way eac3to can work out if its padded or true 24bit. If its padded it'll do a second pass and remove the padding and if its 24bit it will stay as 24bit and I can then run it through eac3to again with -down16? (yeah more time consuming but its the computer doing the work, not me )
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Old 31st May 2010, 23:18   #10047  |  Link
~Revolution~
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I don't get the point of padding 16bit to 24bit in the first place. What does it exactly do?
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Old 31st May 2010, 23:19   #10048  |  Link
hubblec4
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Quote:
Originally Posted by madshi View Post
eac3to v3.19 released

http://madshi.net/eac3to.zip

Code:
* added support for 3D Blu-Rays (playlists, detection & demuxing)

(Before anybody asks: The "left eye" stream is a normal h264 stream, which every h264 decoder supports. The "right eye" stream is a special h264 extension stream which current h264 PC decoders don't understand.)


thats wonderful news. I hope this issue with the "right eye" stream will be fixed at someone next time.

thanks for your working on eac3to.
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Old 31st May 2010, 23:54   #10049  |  Link
iSeries
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@~Revolution~ - Doesnt make sense to me either!
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Old 1st June 2010, 04:03   #10050  |  Link
Xorp
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Quote:
Originally Posted by ~Revolution~ View Post
I don't get the point of padding 16bit to 24bit in the first place. What does it exactly do?
http://forum.doom9.org/showpost.php?...postcount=9868

If eac3to kept it flagged as 16-bit like the source, some decoders might only decode in 16-bit, so madshi smartly made eac3to flag all DTS as 24-bit just in case
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Old 1st June 2010, 06:53   #10051  |  Link
madshi
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Quote:
Originally Posted by iSeries View Post
So, I'll get better quality on padded sources if I first demux/convert to .wav? That way eac3to can work out if its padded or true 24bit. If its padded it'll do a second pass and remove the padding and if its 24bit it will stay as 24bit and I can then run it through eac3to again with -down16?
Yeah, for max quality that would be the best approach.
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Old 1st June 2010, 07:14   #10052  |  Link
mrr19121970
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Quote:
Originally Posted by tvjunky View Post
Would it be much work to automatically create a second file containing only the forced captions while extracting this stream?
Quote:
Originally Posted by madshi View Post
I guess it would be possible, but I don't know how difficult it would be. I'll put it on my to do list.
Whilst eac3to is back in focus, I'm wondering if you'd had time to think about extracting forced subs into an extra file?
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Old 1st June 2010, 07:22   #10053  |  Link
madshi
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Quote:
Originally Posted by mrr19121970 View Post
Whilst eac3to is back in focus, I'm wondering if you'd had time to think about extracting forced subs into an extra file?
It is on my to do list - like so many other things I'd like to add to eac3to. I'm currently lacking time, though. And the time I can find for HTPC development mostly go into madVR at this point, since madVR is still a work in progress, while eac3to is pretty stable. There probably will come a time when I come back to eac3to with more development resources, but it's not here yet right now. (3D was important and easy to add.)
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Old 1st June 2010, 08:18   #10054  |  Link
dansrfe
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So are there any decoders which decode non 24-bit padded 16-bit DTS properly and account for the variations in frequency domain representation when the PCM audio is recreated during decoding? Does ffdshow audio decoder properly do that with the 24-bit padding? Also I've always been curious to know why are there different outputs for the different bit integers. I have checked only 32 bit floating point because I assumed it was the "best" option and gives the decoder lots of "room" for whatever it needs to do though it might unnecessarily raise cpu usage since the decoding actually only needs 24-bit for 16-bit Digital Dolby or DTS audio.
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Old 1st June 2010, 08:28   #10055  |  Link
madshi
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Quote:
Originally Posted by dansrfe View Post
So are there any decoders which decode non 24-bit padded 16-bit DTS properly and account for the variations in frequency domain representation when the PCM audio is recreated during decoding?
Huh? You're confusing me.

Standard DTS is never padded 16bit. It's floating point.

DTS-MA is usually also never padded 16bit. It's either 16bit, and then the decoder outputs 16bit. Or it's 24bit and then the decoder outputs 24bit.

The only situation where 16bit -> 24bit padding usually occurs is with TrueHD/MLP tracks. I've seen tons of DTS-MA tracks and their bitdepth information is usually correct. I've only ever seen one single DTS-MA track which was flagged as 24bit, but only contained 16bit data, while I've seen hundreds of DTS-MA tracks which were flagged correctly.
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Old 1st June 2010, 08:52   #10056  |  Link
dansrfe
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Sorry I should have been more clear in my wording. What I meant to say was that is there any decoder which will correctly decode DTS audio encoded from 16-bit and which has not been flagged as 24-bit?
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Old 1st June 2010, 10:01   #10057  |  Link
madshi
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That still doesn't make any sense. Are you talking about standard DTS or DTS-MA?
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Old 1st June 2010, 10:23   #10058  |  Link
dansrfe
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Standard DTS. The link in some posts above said that when standard dts is converted to PCM via decoding it is 8 bits more therefore some decoders need the 24-bit padding in order to have all the bits that's why I was wondering if there are any decoders that can play without the padding and still anticipate 8 bits more when decoding.
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Old 1st June 2010, 10:25   #10059  |  Link
madshi
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I don't know for sure which decoders are outputting what, if eac3to doesn't patch the bitdepth to 24bit. ArcSoft outputs 16bit without the patching, I think. To which bitdepth libav/ffmpeg decodes, depends on the libav/ffmpeg version and the decoder/media player which uses it. If you decode by using eac3to, you will always get full bitdepth.
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Old 1st June 2010, 12:25   #10060  |  Link
TinTime
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madshi

A bit more info - I've been looking further into the problem I reported with reducing the bitdepth of 24 bit audio.

It seems to be near peak values that don't necessarily have their depth reduced. Presumably dithering means that a value can be rounded up or down. However near the peak I suppose the value should always be rounded down - ie truncated.

For example the centre channel in the test file I posted contains the following sequence of samples (as wav):

Code:
24 bit in     20 bit out
EC 65 77      F0 65 77
FC FF 7F      FF FF 7F
FE FF 7F      FF FF 7F
FD FF 7F      F0 FF 7F
51 E8 5C      50 E8 5C
I reran my test file through eac3to using...
Code:
eac3to.exe "test1 24.flac" "test1 20.flac"  -1dB -down20
...and it worked correctly. In fact perhaps this is the correct approach. The bit depth reduction in this case would introduce clipping otherwise.

Last edited by TinTime; 1st June 2010 at 13:03. Reason: Initial post incorrect
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