cant hear LFE

[anders@dac.se]

I'm making an amature movie with dolby 5.1 sound. I've made all the channel except the LFE channel. How should i prepare it? Should i take away all of the High freq's? Or isnt the LFE for low freq sounds?

[DSPguru]

LFE=Low Frequency Effect


usually made with elliptic filter of 8th order with cutoff frequency of 120hz.

[anders@dac.se]

when i try to make an DVDimage out of an project Sonic scenarist tells me that it cant be done beacause of "LFE channel are different between dolby AC3 T01 3_2ch 448Kb and trailer_2."

What am i doing wrong?

/Anders

[anders@dac.se]

made a question too fast :) I found out that its not anough to add teh LFE channel to the project, you also need to enable LFE under the options menu.. whopps :)

/A

[anders@dac.se]

i've made an AC3 track both in Soft Encode from Sonic and the encoder shipped with scenarist.

I've made an LFE PCM wav fith a cutoff filter at 120 hz

i've checked the "Enable LFE" option. But i cant hear the LFE when i listen to the AC3 track.. Whats wrong?

/Anders

[DSPguru]

try decoding your ac3 to 6 mono waves with BeSweet and check if the LFE file isn't empty..

[anders@dac.se]

when I open it in SOFT Encode it looks like the LFE is empty..
It is a LFE track, but its empty, no signals...

But im sure that i've added a LFE track when i encoded the AC3...

/Anders

[DSPguru]

can you describe your encoding process in detail?

[anders@dac.se]

i make 48khz 16 bits mono wavs for each channel in premiere (my entire movie is edited in premiere).
now i got 5 mono files. i also make a wav in premiere where all tracks are combined into a mono wav, i open it in cool edit and filter it to 0-120 hz (My LFE channel).

I then open the encoder that comes with scenarist (or Soft Encode)

Open the wav for each channel, i enable LFE channel in options, and select data and sample rate to 448 and 48....

Thats every thing.. and if i play or open the final AC3 the LFE is gone... :(

Thanks for all the help,

/Anders

[DSPguru]

weird.
i've encoded tracks with soft encoder, and it did work.
are you sure that Cool Edit's LFE product is correct ?

[anders@dac.se]

I dont know, does it have to be at an EXACT way?

I don think that cool edit cuts off at the 8 order... The curve looks weird.. But i have selected the 8 order in cool edit...

What program do you use to filter?

/Anders

[anders@dac.se]

By the way, if you want to, and have TIME.. I understand if you dont have time, but if you do, could you download this file, you could try to encode it and se if it works..

ftp://guestuser:guestuser@ftp.dac.se/surroundtest.zip

Its on about 2 megs.. It's a surround test i've made (not encoded, in wavformat), all other channels than the LFE works like a dream, the LFE test kicks in at 38 seconds, and its completly silent, if you open the encoded AC3 in softencode you get a flat lined curve, the other channels have signals, and you can hear them...

Thanks in advance, Anders

/Anders