Inserting a "blank" channel

[pat bateman]

Hello All,

I have a 5.0 surround file that has a blank LFE channel. The channel is there in the audio file, but there is no sound and appears to be completely empty. The problem is, my AVR will not recognize the file as multi channel without *something* being in the LFE channel. Is there a way to insert something into that channel that only my receiver will "hear" so it will register as multi-channel?

Thank you for any help!

 

[LuvMyQuad]

I have never heard of this problem before. It seemed as long as the channel was actually there, even though it was blank, it would trick the decoder chips into playing it back as multi channel. Beyond that, I thought 5.0 was a valid, modern, multichannel format. What AVR is it? Maybe someone else that has the same model can comment further.

 

[timbre4]

First as others have suggested, tell us which AVR you have and we can better assist you.

Seems to me also that it should play with 5 channels. I just 'corrected' a whole 4.0 quad folder of FLACs by using MMH 5 to add a 5th silent channel. Now the Denon AVR-X2200 in the living room system plays them as 4.0 quad instead of treating them as 2 channel (fronts only) stereo. The older AVR plays the 4.0 originals without issue.

I do not recall which channel it went into LFE or center but I'm sure we can find out. There are options to explicitly add it in LFE or center. This is the thread to learn more if needed: [curated by the quiet genius himself almost daily]
https://www.quadraphonicquad.com/fo...seful-tools-for-music-videos-mch-audio.22693/

 

[LuvMyQuad]

First as others have suggested, tell us which AVR you have and we can better assist you.

Seems to me also that it should play with 5 channels. I just 'corrected' a whole 4.0 quad folder of FLACs by using MMH 5 to add a 5th silent channel. Now the Denon AVR-X2200 in the living room system plays them as 4.0 quad instead of treating them as 2 channel (fronts only) stereo. The older AVR plays the 4.0 originals without issue.

I do not recall which channel it went into LFE or center but I'm sure we can find out. There are options to explicitly add it in LFE or center. This is the thread to learn more if needed: [curated by the quiet genius himself almost daily]
https://www.quadraphonicquad.com/fo...seful-tools-for-music-videos-mch-audio.22693/

I thought with 5 channels and no LFE, the 3rd channel is assumed to be the center. If there are 6 channels, the 3rd is the center, the 4th is the LFE. Is that wrong?

 

[J. PUPSTER]

I thought with 5 channels and no LFE, the 3rd channel is assumed to be the center. If there are 6 channels, the 3rd is the center, the 4th is the LFE. Is that wrong?

I don't know about 5 point nothing? I just ripped this new one today (nice listen BTW)
https://www.quadraphonicquad.com/fo...er-side-live-in-notre-dame-in-surround.30833/
and it has no LFE at all, seemed to play OK with FB2K on my computer, but I dropped an empty LFE in just for good measure in case my oppo wants to spit it up like a hairball

and to Pat's (OP) problem, I've never heard that one before either, maybe try copying the center channel and do a High Pass Filter at say 19K for the LFE, at least there'd be something in there.

 

[LuvMyQuad]

I don't know about 5 point nothing? I just ripped this new one today (nice listen BTW)

and it has no LFE at all, seemed to play OK with FB2K on my computer, but I dropped an empty LFE in just for good measure in case my oppo wants to spit it up like a hairball

Yeah, I drop empty CC and LFEs into everything, So all my MC rips are 6 channels. I don't need problems down the road, and the extra size from empty channels is virtually nothing.

 

[pat bateman]

Thank you for all the replies ya'll. I re-ripped and the problem went away. Very weird.

 

[timbre4]

I thought with 5 channels and no LFE, the 3rd channel is assumed to be the center. If there are 6 channels, the 3rd is the center, the 4th is the LFE. Is that wrong?

I believe that’s right. They open in Sound Forge that way.

 

[timbre4]

Thank you for all the replies ya'll. I re-ripped and the problem went away. Very weird.

Good! So what we were thinking still holds up.

 

[jimfisheye]

Sounds like you got to the bottom of a random error?

FYI, digital silence IS something! A stream of PCM audio data that just happens to be silence.

For the theory of a silent track causing trouble, that would mean the receiver is doing DSP on the audio and making a determination not by the channel format it sees, but by also qualifying the audio content. Someone would have had to program that behavior. Talk about opening a can or worms, right?

Just a sanity check for any future troubleshooting!

Media players read the header for the channel format. They don't care what's in the audio. Just that there's a stream of some audio there.

 

[LuvMyQuad]

Media players read the header for the channel format. They don't care what's in the audio. Just that there's a stream of some audio there.

So when we add a blank channel does something edit the header? Or is the header determined when the player scans the number of channels?

 

[jimfisheye]

So when we add a blank channel does something edit the header? Or is the header determined when the player scans the number of channels?

There are file formats. When you render a 5.1 file, the file header created indicates that. No channels are scanned in any way. The file header is assumed to be correct.

If you did something manually like try to add the extra channel data with a hex editor and then didn't alter the bits in the header portion of the file... You'd have to do something non-standard intentionally or have buggy software that did that for you. Hitting render in any DAW app will automatically make the header info for the type of file you are creating.