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2nd June 2020, 19:42 | #1 | Link |
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Down Sizing ATMOS or TrueHD 7.1
Hey guys, since the forum is quiet lately I thought I would ask jdobbs or anyone else on this esteemed forum how they are dealing with all the ATMOS or TrueHD 7.1 audio that is on most disks nowadays. I always used to keep 7.1 audio intact before ATMOS came along with the outrageous 5GB or more file sizes. I'm not willing to keep this on a BD25 project at the expense of the video. I have been happy to keep just the Core 5.1 @ 1500K but here lately keeping the core only gets me DD5.1 @448. How do I get better audio?
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2nd June 2020, 22:05 | #3 | Link |
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Thanks gonca, which tool would you recommend for this purpose? I don't have much use for command line stuff but maybe I could find a GUI for it somewhere. Also are you talking about just keeping the TrueHD 7.1? I thought that that is what BD Rebuilder was converting to get the core 5.1 448K audio. Sorry if I am just being dumb (my normal resting state), lol.
Last edited by worknstiff; 2nd June 2020 at 22:10. Reason: more info |
3rd June 2020, 01:34 | #5 | Link |
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I don't know if there are a free tool to keep only the TrueHD 7.1 and reject the Atmos metadata. BTW I don't think downsize it very much.
You can use ffmpeg to recode the Atmos to AC3 5.1 until 640 Kb/s, or to EAC3 5.1 to your desired bitrate (but not used in BD's). To preserve 7.1 with free encoders you need use AAC, also not supported in BD's.
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3rd June 2020, 05:08 | #6 | Link |
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(Removed, its actually possible), what I do is convert the original file to DTS-HD Master Audio 16 Bits, bitrate savings are enormous, in some cases going from 6500 Kbps to 2500 Kbps while still been a lossless track.
Last edited by SquallMX; 3rd June 2020 at 16:33. |
3rd June 2020, 10:59 | #8 | Link |
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@ SquallMX; RE: what I do is convert the original file to DTS-HD Master Audio 16 Bits, bitrate savings are enormous, in some cases going from 6500 Kbps to 2500 Kbps while still been a lossless track.
That's exactly what I wish to do. What do you use to convert? |
3rd June 2020, 13:52 | #9 | Link |
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You are right richardpl, I obtain the TrueHD without Atmos using:
ffmpeg -i Atmos.thd -bsf truehd_core -acodec copy No-Atmos.thd And I'm was wrong, the downsize is really noticeable 4,5 GB -> 3.1 GB If you want less size but better than the AC3 core with only 448 Kb/s you can recode for free to AC3 640 Kb/s 5.1 (max): ffmpeg -i Atmos.thd -c:a ac3 -b:a 640k -center_mixlev 0.707 No-Atmos5.1.ac3 Size test using the unique TrueHD Atmos in spanish language than I know (Valerian...): Original audio track, L: max 22 bits, average 20 bits. Original audio track, R+C+BL+BR+SL+SR: max 24 bits, average 20 bits. Original audio track, LFE: constant bit depth of 20 bits. Duration ....: 8217,08417 sec., (2h. 16m. 57.08417s.) Using 24 bits encodes Code:
File Chan. Size Kb/s % ------------- ----- ------------- ---- --- No-Atmos.w64 7.1 9.466.081.088 9216 100 Atmos.thd X.1 4.837.954.028 4710 51 (source) No-Atmos.dtshd 7.1 3.911.958.756 3809 41 No-Atmos.thd 7.1 3.334.975.156 3247 35 No-Atmos.flac 7.1 2.944.181.915 2866 31 No-Atmos.ac3 5.1 657.367.040 640 6.9 No-Atmos.aac 7.1 643.377.934 626 6.8 (V 100) Code:
File Chan. Size Kb/s % ------------- ----- ------------- ---- --- No-Atmos.w64 7.1 6.310.720.768 6144 100 No-Atmos.dtshd 7.1 2.540.000.084 2473 40 No-Atmos.flac 7.1 1.730.972.249 1685 27 If your TrueHD track is not 16 bits, like the mine, your dtshd downsampling to 16 bits is not lossless. The truehd_core have less size than the dtshd 24 bits. To encode to dtshd you need DtsHD Master Audio Suite really expensive. EDIT: my choice is preserve the Atmos with a full 3D surround (I have a system Atmos 5.1.2) I never use 7.1 no-Atmos because to obtain a 2D surround is enough 5.1 channels, then my choice was AC3 5.1 640 Kb/s without audible diference with lossless 5.1 If the AC3 core is only 448 Kb/s like here I recommend use MeGUI or BeHappy (32 bits) to downmix 7.1 to 5.1, using AudioLimiter.dll, and ffmpeg to recode to AC3 5.1
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 3rd June 2020 at 14:35. Reason: add info |
3rd June 2020, 16:30 | #11 | Link | |
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Quote:
But, would a 448 kbps file encoded with an official Dolby software provide more quality than a 640 Kbps created with Aften or FFMPEG?, last time I check Aften was not using all the potential of the AC3 specs and had some volume issues when decoding on standalone devices. |
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3rd June 2020, 21:25 | #12 | Link | |
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Quote:
But you might just as well strip out the ATMOS and use the 7.1 thd track Last edited by gonca; 3rd June 2020 at 21:28. |
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4th June 2020, 00:17 | #13 | Link | |
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Quote:
Yes, with ffmpeg.
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4th June 2020, 15:23 | #15 | Link |
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I never used BD_RB and maybe you are rigth about aften encoder (nicaudio is the avisynth decoder).
I download the last version v0.61.05 and I see some old soft in Tools subfolder. Some tips for jdobbs about audio soft: 19/01/2008 aften.exe Obsolete must be replaced by ffmpeg 09/12/2011 aften2.exe Obsolete must be replaced by ffmpeg 10/01/2015 AudioLimiter.dll OK, seems the downmix use that plugin like I recommend. 11/03/2010 faac.exe Obsolete must be replaced by ffmpeg 14/07/2012 faad.exe Obsolete must be replaced by ffmpeg 30/11/2017 ffmpeg.exe maybe is better to upgrade it (the -bsf truehd_core is added in 2019) 27/08/2012 nicaudio.dll Thanks for use my last version but I recommend replace it with LSMASHSource.dll with HD audio support and much more codecs than NicAudio 24/08/2012 wavi.exe There are a new Chizuken version here and a rewrite rewavi
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10th June 2020, 13:36 | #16 | Link |
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Thanks tebasuna51, on your recommendation to use MeGUI or BeHappy to recode to AC3 5.1. I will have to try it. I have even been attempting to extract each channel to wav and then use SoundForge to create 5.1 output, but that creates a file that BD Rebuilder doesn't like to recognize. Plus it is a time consuming process when I can just use CloneBD and it will create 5.1 @640 from somewhere, lol.
Thanks again, tebasuna51! |
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