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19th March 2011, 01:13 | #1 | Link |
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Editing AC3 header information...
I found a couple of threads about this, but they all ended in discussions about why the question was asked, not if there was a way to do it...
Is there a tool out there that can edit the header of an AC3 file? I need to change the Dolby Prologic surround flags in a bunch of AC3 files, and was looking for a tool to allow me to do that (without re-encoding, just changing the header info...) Being able to change all the settings would be nice (Bitstream mode, dial norm, input filtering, etc...), but the surround flag is an important one right now... Any help? I tried encoding the same file with and without Prologic too look at what has changed, but the flag that is changed is different on every 'frame' of audio apparently... Simple search&replace won't work. |
19th March 2011, 02:53 | #2 | Link |
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- Bitstream mode, for what?
- input filtering, to late the signal was already filtered. - Dial Norm, you can use eac3to (or DN31-Ac3.exe attached). - Set the DPL flag, you can use DplAc3.exe attached. [EDIT] New attachement here including also SplitAc3, DNx_eac3 with sources and 64/32 bits versions. The DNx_ac3 and DNx_eac3 are now DNx_Any and solving a bug detected in DNx_eac3
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 29th September 2021 at 16:59. Reason: update link |
19th March 2011, 04:06 | #3 | Link | |
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Quote:
Bitstream Mode, options are: Complete Main Music & Effects Visually Impared ... Etc. Not sure what they do actually, just one of the options in the encoder. Never know when you might need to change something. RF overmodulation, is that a 'flag', or does it actually change the audio during encoding? Something I'd like to be able to turn off without re-encoding, if that's an option. Being able to change the prologic flags will be a huge help, thanks a lot for that! Will this allow changing between all 3 settings, or does it just turn PL on? Thanks again, Rik |
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19th March 2011, 04:35 | #4 | Link |
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To know about data en AC3 header read:
Digital Audio Compression Standard (AC-3, E-AC-3) Revision B DplAc3.exe turn PL on.
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19th March 2011, 10:47 | #6 | Link |
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I don't know.
But you have the code, isn't difficult make the changes: 1) Read 1 frame 2) Change the value 3) Reconstruct crc1 4) Goto 1 until end of file
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16th April 2011, 07:01 | #7 | Link | |
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Quote:
You may use Code:
change_dn.exe input.ac3 DN For testing this tool you may use test.exe Code:
test.exe 1.ac3 27 FileSize : 315820288 bytes SamplCod : 0 (2=32, 1=44.1, 0=48 KHz.) BitRate : 448 Kb/s FrameSize: 1792 bytes DialNorm: -31db 0xXX 0xXX Second - other frames. Of course, they must coincide. If ac3 is mono then hex-values will be for example Code:
3b 80 3b 80 3B 80 = 00011101 10000000 11011 = 27 If 3/2 (L, C, R, SL, SR) или 3/1 (L, C, R, S) Code:
DC DC 0xDC = 11011100 (bin) 11011 = 27 Else DN bits are bits beginning 15 bit of BSI Code:
с3 60 с3 60 11011 = 27 -------- Russian forum tebasuna51, thanks for source. Last edited by tebasuna51; 14th January 2013 at 13:22. Reason: Add attachment to avoid dead links |
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14th January 2021, 12:20 | #10 | Link |
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Hi, is it possible to modify ChangeDN to work on E-AC3 files too?
E-AC3 Specification Sample E-AC3 file Currently, the tool gives a crc1 error. |
16th January 2021, 19:46 | #11 | Link |
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@junh1024
This one work with your sample: [EDIT]DNx_eac3.exe and DNx_ac3.exe included in AC3Util.7z in the second post
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 12th June 2021 at 17:45. |
17th January 2021, 11:05 | #12 | Link |
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Thank you tebasuna51, it seems to work on EC3 files of other bitrates . Can I upload the sources & binaries from this thread to Github as a backup?
PS: The EC3 is actually EC3 Atmos, so hopefully they still work on AVR. |
3rd October 2021, 13:11 | #14 | Link | |
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Quote:
Because the eac3 management was buggy, the new one DNx_Any work now for AC3 or EAC3. But I can confirm the MKVToolNix issue, even with the CRC correct in my new version, my AVR (Denon) can't play like Atmos the modified EAC3. I have a EAC3 Atmos with DN -14 tha play at very low volume, changed to DN -31 play at high volume but not like Atmos, changed one more time to -14 my AVR play like Atmos again.
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