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Old 20th September 2014, 01:28   #12801  |  Link
nevcairiel
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Unless someone fixes the TrueHD decoder in ffmpeg/libav, AND you get a new eac3to version which uses the fixed decoder, there is nothing anyone can do.
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Old 20th September 2014, 06:10   #12802  |  Link
asarian
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Quote:
Originally Posted by gillie View Post
Just tried to use eac3to to convert TrueHD to DTS on the new Transformers Age of Extinction Bluray and it will not work at all.
Guessing this will become more of an issue as more and more Blurays are released with the new Dolby Atmos extensions embedded in the TrueHD tracks.
Unless anyone has any ideas on how to sort this?
Yeah, this is no good. Just downloaded and tried the sample myself, and it's a no-go.

So, does this mean my Marantz HD Amp won't be able to even play this? (not at home right now to try). If so, I will be real upset. And, if so, all the more reason for eac3to to find a way to decode it, after all, so I can convert it to LPCM.
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Old 20th September 2014, 09:17   #12803  |  Link
madshi
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Anybody posted this issue to the eac3to bug tracker yet?
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Old 20th September 2014, 18:07   #12804  |  Link
asarian
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Originally Posted by madshi View Post
Anybody posted this issue to the eac3to bug tracker yet?
Not sure it qualifies as a bug per se. Since the Atmos TrueHD stream is said to be fully backwards compatible (= can be played on regular players), I can only draw the conclusion, that they put the Atmos 'ceiling' channels into the metadata (which receivers are supposed to ignore; which is why this works, I presume).

So, all we really need is a knowledgeable coder (you?!) who will strip off the metadata, so we have a regular TrueHD stream again, right?
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Old 20th September 2014, 18:37   #12805  |  Link
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imho it would be preferable being able to decode the entire stream completely.
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Old 20th September 2014, 18:50   #12806  |  Link
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When I use the command to extract the Dolby Atmos to mono wavs. I get this error:

Code:
eac3to v3.24
command line: eac3to.exe  "trans.4.thd+ac3" Vie.wavs
------------------------------------------------------------------------------
The format of the source file could not be detected.  <ERROR>
I think maybe eac3to can not recognize that TrueHD (Dolby Atmos type).
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Old 20th September 2014, 18:51   #12807  |  Link
nevcairiel
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Quote:
Originally Posted by Thunderbolt8 View Post
imho it would be preferable being able to decode the entire stream completely.
You can't just "decode" Atmos, thats not how it works, its not comparable to any audio codec you dealt with before. It effectively needs to be rendered based on the configuration of speakers in your room, which means its unlikely to be easily supported by the existing software solutions for a long time to come (first because we have absolutely no idea how the Atmos data is structured, and secondly because we would need a lot of new code and configuration potential to actually be able to render the audio in a 3D space). If you want, consider it "3D Audio", which is fundamentally different than the previous "2D Audio" we used so far.

Regarding getting the original TrueHD stream out, its not that easy, its not just metadata you have to ignore, its properly integrated into the TrueHD codec itself, and will need proper fixing of the decoder.
Its possible that it would work if we had an "official" TrueHD decoder or a specification, but since the ffmpeg/libav TrueHD decoder is practically reverse engineered, it lacks the ability to deal with those streams, for now.
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Last edited by nevcairiel; 20th September 2014 at 18:56.
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Old 20th September 2014, 18:59   #12808  |  Link
asarian
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Quote:
Originally Posted by nevcairiel View Post
Regarding getting the original TrueHD stream out, its not that easy, its not just metadata you have to ignore, its properly integrated into the TrueHD codec itself, and will need proper fixing of the decoder.
Then I wonder how current receivers are able to play the Atmos-enhanced TrueHD stream just fine, if the Atmos data were really a part of the main TrueHD stream. There's obviously some 'easily' discardable info, or current receivers would not be able to pull it off cleanly.
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Old 20th September 2014, 19:44   #12809  |  Link
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Like I said, if we had the specification of TrueHD, it could tell us what is wrong, but since Dolby is not giving that out, its not that easy.
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Old 20th September 2014, 22:10   #12810  |  Link
Thunderbolt8
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Quote:
Originally Posted by nevcairiel View Post
You can't just "decode" Atmos, thats not how it works, its not comparable to any audio codec you dealt with before. It effectively needs to be rendered based on the configuration of speakers in your room, which means its unlikely to be easily supported by the existing software solutions for a long time to come (first because we have absolutely no idea how the Atmos data is structured, and secondly because we would need a lot of new code and configuration potential to actually be able to render the audio in a 3D space). If you want, consider it "3D Audio", which is fundamentally different than the previous "2D Audio" we used so far.

Regarding getting the original TrueHD stream out, its not that easy, its not just metadata you have to ignore, its properly integrated into the TrueHD codec itself, and will need proper fixing of the decoder.
Its possible that it would work if we had an "official" TrueHD decoder or a specification, but since the ffmpeg/libav TrueHD decoder is practically reverse engineered, it lacks the ability to deal with those streams, for now.
well whatever the wording is, what I meant is its rather preferable being able to use 100% of thats whats there compared to stripping something off in order to get just to the normal THD track.

Quote:
Originally Posted by nevcairiel View Post
Like I said, if we had the specification of TrueHD, it could tell us what is wrong, but since Dolby is not giving that out, its not that easy.
maybe the guy knows who told madshi how to deal with the TrueHD track headers back then when there were those THD delay problems because madshi accidentally stripped too much from these tracks.
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Old 21st September 2014, 03:29   #12811  |  Link
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Quote:
Originally Posted by nevcairiel View Post
Unless someone fixes the TrueHD decoder in ffmpeg/libav, AND you get a new eac3to version which uses the fixed decoder, there is nothing anyone can do.
Patch posted.
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Old 21st September 2014, 03:56   #12812  |  Link
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Hendrik Leppkes is nevcairiel...
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Old 21st September 2014, 04:28   #12813  |  Link
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How to use it?
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Old 21st September 2014, 04:36   #12814  |  Link
asarian
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Quote:
Originally Posted by foxyshadis View Post
Hmm, should I just get this Dev version? Can't compile on Windows myself.

And, even though I understand it's just temporary, I would *still* like ffmpeg/eac3to to retain the option to merely extract the TrueHD core (akin to extracting an AC3 core from the TrueHD stream), so as to have something playable/usable on my system.

P.S. Thanks for the speedy patch!
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Old 21st September 2014, 04:43   #12815  |  Link
tebasuna51
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Quote:
Originally Posted by asarian View Post
... to extracting an AC3 core from the TrueHD stream), so as to have something playable/usable on my system.
The AC3 from the track can be extracted with tsMuxeR, at least with the sample uploaded here.
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Old 21st September 2014, 04:46   #12816  |  Link
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Originally Posted by tebasuna51 View Post
The AC3 from the track can be extracted with tsMuxeR, at least with the sample uploaded here.
Yes. What I meant, though, is the ability to extract the TrueHD stream, like we extract the AC3 stream now. I have no interest in the AC3 core, of course.
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Old 21st September 2014, 05:36   #12817  |  Link
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Quote:
Originally Posted by minhjirachi View Post
How to use it?
Yeah, someone please tell us where this alleged patch resides: the 'posted' patch is just a mailing list post.

I tried the latest binary, and it says:

Code:
c:\eac3to\ffmpeg -i "test.m2ts" -vn -ac 8 -acodec pcm_s24le -f wav c:\video\temp.wav

[truehd @ 02bb57e0] major sync info header checksum error
    Last message repeated 42 times
[NULL @ 02bb57e0] start time for stream 1 is not set in estimate_timings_from_pts
[mpegts @ 02bb9080] Could not find codec parameters for stream 1 (Audio: truehd (AC-3 / 0x332D4341), 0 channels): unspecified sample format
It *does* extract a stream, btw, but, upon conversion (and downmixing) to LPCM, eac3to says:

Code:
Mixing surround channels...
Writing WAV...
Creating file "c:\video\finak.wav"...
Original audio track, L+R+C+LFE+SL+SR: constant bit depth of 24 bits
Original audio track, BL+BR: no audio data.
The processed audio track has a constant bit depth of 24 bits.
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Old 21st September 2014, 06:59   #12818  |  Link
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Looking at ffmpeg's git log, the patch wasn't merged in yet... So using the latest precompiled binary won't do you any good.
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Old 21st September 2014, 07:02   #12819  |  Link
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Hendrik Leppkes is nevcairiel...
Oh, I had no idea. Thank you, nev!
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Old 21st September 2014, 07:02   #12820  |  Link
asarian
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Originally Posted by Superb View Post
Looking at ffmpeg's git log, the patch wasn't merged in yet... So using the latest precompiled binary won't do you any good.
Yeah, I noticed (when I found the log); seems latest compile was yesterday's. Thx.
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