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4th February 2007, 17:08 | #1 | Link |
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Join Date: May 2006
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lowpass filter when encoding ac3
Morning,
Downmixing 6ch wav to 5.1 ac3 using BeSweet. Is there a CLI switch that I may use to control whatever the preset freq is for the lowpass filter to LFE? I would like to remove bass from all other channels and send directly to LFE. I can set that from the BeSweet GUI "Azid 1" settings page, correct, by checking "LFE to LFE output" box? Am I not seeing an option to adjust that freq, somewhere? Also, since I am selecting LFEto LFE in the DOWNMIX LEVELS area , in the OUTPUT MODES area, should I select DECODE(Front/Rear) 3/2? I know that LAME has --lowpass switch. Can that work with Azid as well? Thank You. |
5th February 2007, 11:32 | #2 | Link | |||||
foobaring my ass off
Join Date: Nov 2005
Location: Argentina
Posts: 618
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Quote:
2) DonŽt use BeSweet for AC3 encoding, its ac3enc.dll is a low quality encoder. Quote:
Lowpass filters for LFE in AC3 are about 120 Hz (should ask what frequencies Aften developers are using for lowpass), though Vegas, in its project settings has an option for setting the lowpass to use with the LFE channel , and offers 4 choices: - 80 (Dolby consumer/DVD) - 116 (DTS) - 120 (Dolby pro/film) - 180 Quote:
LFE to LFE Output controls the gain the LFE channel will have if directed to the LFE output(as in no downmixing of the LFE into other channels is being done). 0 gain (no gain) means the LFE will go untouched to the LFE output of the output file. If you want to send the low frequencies from all the channels to the LFE, youŽll need an advanced audio editor with some frequency filtering capabilities. Quote:
Code:
BeSweet.exe -core( -input 6ch.wav -output 6ch.ac3 -logfile BeSweet.log ) -ac3enc( -b 448 -6ch ) Quote:
Cheers
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5th February 2007, 14:12 | #3 | Link |
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Join Date: May 2004
Location: Montreal
Posts: 729
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Just remember that if you do remove frequencies and send them only to the LFE, and then use the file to create a DVD or surround CD, these frequencies will be completely lost for playback on Dolby Pro Logic systems, as the LFE data is discarded.
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