inserting silence at the beginning of multi-channel FLAC

[mdubin]

Hi:

I have a 6 channel (5.1) single flac file which contains the image of an album. I also have an associated cue file. When I play this file from a USB Flash Drive connected to my Blu-ray player, I lose about 1-2 seconds because my receiver (like most) is a bit slow to initialize a multi-channel digital signal.

My solution (I think) would be to add a few seconds of silence to the beginning of this flac file.

Now when I load the flac file into audacity, I do see 6 channels all of them showing as “mono”. I hope this is correct as I would expect them to appear as left, right, center, left surround, right surround, LFE.

Anyway, I go into “generate: silence” and add a few seconds at the very beginning.

Then I do the export, making sure that “custom mix” is enabled in my preferences. I set the bit rate to 24 which corresponds to that of the imported file and then I do see an advanced mixing box which indicates 6 channels. I click OK and save the FLAC.

Will this method preserve the multi-channel specs and audio quality of the original file exactly or will there be some difference in the sound of the original versus the exported file?

Thanks in advance for your response.

mdubin

[Gale_Andrews]

@mdubin

I have a 6 channel (5.1) single flac file which contains the image of an album. I also have an associated cue file. When I play this file from a USB Flash Drive connected to my Blu-ray player, I lose about 1-2 seconds because my receiver (like most) is a bit slow to initialize a multi-channel digital signal.

My solution (I think) would be to add a few seconds of silence to the beginning of this flac file.

Now when I load the flac file into audacity, I do see 6 channels all of them showing as “mono”. I hope this is correct as I would expect them to appear as left, right, center, left surround, right surround, LFE.

Files don’t always obey the rules, but the recommendation for FLAC is for LFE as fourth channel in 5.1 - https://xiph.org/flac/format.html#frame_header ( scroll down a little).

@mdubin

Anyway, I go into “generate: silence” and add a few seconds at the very beginning.

Then I do the export, making sure that “custom mix” is enabled in my preferences. I set the bit rate to 24 which corresponds to that of the imported file and then I do see an advanced mixing box which indicates 6 channels. I click OK and save the FLAC.

Will this method preserve the multi-channel specs and audio quality of the original file exactly or will there be some difference in the sound of the original versus the exported file?

You will have to listen to the exported file in your surround sound equipment. You can drag the Audacity tracks up and down and re-export if the channel mapping is wrong.

You’ll get dither noise in the export, even if you set Default Sample Format in Quality Preferences to 24-bit. That’s a long-standing bug, but you can set “Dither” under “High-quality conversion” to “None” in Quality Preferences.


Gale