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17th January 2020, 15:05 | #1 | Link |
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Join Date: Nov 2013
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Does FFMPEG convert 5.1 to 2.0 properly by default??
Hi, I normally use ffmpeg+neroaacenc to downmix AC3 and DTS surround to 2 channel AAC using the following command line:
Code:
ffmpeg.exe -y -i SOURCE.MKV -ac 2 -acodec pcm_s16le -f wav - | neroAacEnc.exe -ignorelength -if - -of DESTINATION.AAC So I was just wondering if when ffmpeg downmixes multichannel to 2 channel if it just blindly merges all the channels together or if it makes level adjustments to some of the channels before downmixing. Thanks. Last edited by syrist; 17th January 2020 at 15:07. |
17th January 2020, 21:50 | #2 | Link |
47.952fps@71.928Hz
Join Date: Mar 2011
Posts: 940
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Yeah, it will downmix properly, according to standards. Remember the standards omit the LFE channel.
https://trac.ffmpeg.org/wiki/AudioCh...ion#a5.1stereo You can use the pan audio filter to customize the downmix how you want. https://ffmpeg.org/ffmpeg-filters.html#pan-1
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18th January 2020, 11:56 | #3 | Link | |||||||
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For a standard mix: Quote:
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clev can be: 0.707 (my recommendation when encode: -center_mixlev 0.707) 0.595 (the default when encode with ffmpeg) 0.500 (never recommended) slev can be: 0.707 (not recommended) 0.500 (the default and recommended with ffmpeg) My recommended un-normalizad mix standard is: Quote:
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 19th January 2020 at 13:10. Reason: typo |
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27th January 2020, 20:45 | #4 | Link | |
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Join Date: Nov 2013
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Tags |
downmix, ffmpeg, multichannel, stereo, surround |
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