Topic: Seeking advice on 24 bit matrix

[beatkilla]

OK....I have 2 sources ,a soundboard feed 24/48 and an aud source 24/48.I am doing a matrix to go along with the video sources of the show.I already know how to synch and do matrix with Sony Vegas.So the part i need help with is the (dithering?)resample of the 24 bit audio.I have not worked with 24bit before.The audio will ultimately be 16 / 48 for the DVD,so what steps are needed to accomplish that properly?Should i do that first before the matrix or do my matrix and render to 16/48?

I was messing around with the mix a little and discovered i was liking the sound alot more if i combined the SBD source into 1 mono track.....is that common to do?Any tips on the resample...dithering would be great.

[Brian Skalinder]

Mix the 24/48 sources to 32/48 first, then dither to 16/48.  Some apps allow you to accomplish both the mixing and dithering in one step (in the proper order), other apps require two steps.

I've mixed a mono soundboard with a pair of mics before.  Worked quite nicely.  There's a good chance the board feed was mono, anyway (though perhaps dual mono, i.e. same content both L and R channels).  Nothing wrong with mixing mono sbd with the mics, especially if your ears prefer it. 

[keytohwy]

Since the DVD spec allows for 24/48, why not leave it alone?

keytohwy

OK....I have 2 sources ,a soundboard feed 24/48 and an aud source 24/48.I am doing a matrix to go along with the video sources of the show.I already know how to synch and do matrix with Sony Vegas.So the part i need help with is the (dithering?)resample of the 24 bit audio.I have not worked with 24bit before.The audio will ultimately be 16 / 48 for the DVD,so what steps are needed to accomplish that properly?Should i do that first before the matrix or do my matrix and render to 16/48?

I was messing around with the mix a little and discovered i was liking the sound alot more if i combined the SBD source into 1 mono track.....is that common to do?Any tips on the resample...dithering would be great.

[ShawnF]

Since the DVD spec allows for 24/48, why not leave it alone?

24 bit resolution requires more space.  No idea how long this show was, but if it was long and the highest bit rate for the video encoding is desired, a smaller-sized audio file might be important. 

Also, do all DVD decks output 24 bits via their digital outs?  Maybe the issue I'm thinking of was that many downsampled higher sample rates and the bit rate wasn't affected, but if it is getting truncated to 16 bits by the player, you might prefer to have dithered it down yourself ahead of time.  If your audience is likely not using the audio digital out, though, then it probably doesn't matter.

[jacobmyers]

Since the DVD spec allows for 24/48, why not leave it alone?

24 bit resolution requires more space.  No idea how long this show was, but if it was long and the highest bit rate for the video encoding is desired, a smaller-sized audio file might be important. 

Also, do all DVD decks output 24 bits via their digital outs?  Maybe the issue I'm thinking of was that many downsampled higher sample rates and the bit rate wasn't affected, but if it is getting truncated to 16 bits by the player, you might prefer to have dithered it down yourself ahead of time.  If your audience is likely not using the audio digital out, though, then it probably doesn't matter.

 I know that there are reasons that people give for recording in higher bitrates then dithering down to 16 (mostly because they're planning to mess with the sound in post) but I agree with keytohwy. I'd leave the sound in 24/48 and, if I had to, make it a dual-layer DVD. The people who have good playback systems will thank you for the superior audio and 24 bit sound may just be a selling point for some consumers (which only matters if you're planning to sell the DVD). Of course, you could always make two versions (16 and 24) but that would probably cost more than simply printing a dual-layer DVD.

 May I ask what you're working on? If you're putting it out in 24 bit, I may be interested in a copy... 

[airbladder]

Why go from 24/48 to 32/48 before going to 16/48? 

[Brian Skalinder]

Why go from 24/48 to 32/48 before going to 16/48?

Most WAV editors perform the actual processing at 32bfp, so it's an unavoidable part of the workflow.*  So you have to dither back down to 24-bit or 16-bit no matter what.  Some WAV editors will process at 32bfp and then dither down in one process / dither step, others require a processing step + a manual dither step.

* Unless one configures the audio editor to perform its processing at some other bit-depth, which some software supports.

[John Kary]

I believe Vegas processes audio at 32-bit float.  If so, render the audio out of Vegas at 32-bit float then dither with R8brain to 16-bit. http://www.voxengo.com/product/r8brain/