Thoughts on mixing 24 Bit & 16 Bit sources?

[tbrown4]

So...I've been doing the matrix thing for a while now. I just recently got a 24 bit recorder, which I am using as my primary deck. I still have a 16 bit recorder as my back-up deck. For shows that I'll have soundboard access, I typically use the 16 bit deck to catch the SBD signal and my 24 bit deck to catch my mic recording.

My thoughts are that if I am doing a matrix of the two, the end product is essentially limited to 16 bit. While I could mix the two and export it as a 24 bit file, it wouldn't be true 24 bit depth.

Am I correct in this?

Thoughts?

[dorrcoq]

I think you're right, but either way you have to get the bit rate the same, so upsampling to 24 bit is one option.  Even if it isn't true 24 bit, it allows you to matrix the two sources.  Of course, I've never done this so I could be full of shit.

[datbrad]

So...I've been doing the matrix thing for a while now. I just recently got a 24 bit recorder, which I am using as my primary deck. I still have a 16 bit recorder as my back-up deck. For shows that I'll have soundboard access, I typically use the 16 bit deck to catch the SBD signal and my 24 bit deck to catch my mic recording.

My thoughts are that if I am doing a matrix of the two, the end product is essentially limited to 16 bit. While I could mix the two and export it as a 24 bit file, it wouldn't be true 24 bit depth.

Am I correct in this?

Thoughts?

A buddy of mine has taken my 16 bit source and he upconverted to 24 bit before mixing, then everything was brought back down to 16 bit for the final listening mix. Since analog signal paths rarely have over 120 SNR, you are not recording 24 bit depth anyway, so this should not be a problem mixing the two.

[tgakidis]

Sony vegas pro allows you to mix differnt bit rate sources  and render down to 16 bit. In this case you would not want to render as a 24 bit file.

[tbrown4]

Mixing the sources is not the issue at all. I have mixed various sources of different bit depth and sample rates without dithering or resampling without issue at all. That's quite easy to do in Sony Vegas.

My question was mainly aimed at the finished product rendering essentially being limited to the lowest sample rate and bit depth of the various sources. 

[page]

Mixing the sources is not the issue at all. I have mixed various sources of different bit depth and sample rates without dithering or resampling without issue at all. That's quite easy to do in Sony Vegas.

My question was mainly aimed at the finished product rendering essentially being limited to the lowest sample rate and bit depth of the various sources. 

my Blue Turtle Seduction show in September last year was done this way (24 aud, 16 sbd). You still have 24 full bits in the end product if you render it as such, because (in theory) you are including information from the last 8 bits of the 24bit aud source. Can you realistically hear them in the final mix after bringing in the board? Doubtful, but it's possible, and if you can, they are there.

It's not as good (on paper) as 24 and 24, but 24 and 16 still can have 24bit information, just not much of it.

[tbrown4]

Ah. Ok, that makes sense. Thanks!

In my opinion, that would make it worth doing.

Any other thoughts?

[easy jim]

my Blue Turtle Seduction show in September last year was done this way (24 aud, 16 sbd). You still have 24 full bits in the end product if you render it as such, because (in theory) you are including information from the last 8 bits of the 24bit aud source. Can you realistically hear them in the final mix after bringing in the board? Doubtful, but it's possible, and if you can, they are there.

It's not as good (on paper) as 24 and 24, but 24 and 16 still can have 24bit information, just not much of it.

^  I've done this a few times, mixing 16 and 24 bit sources.  I've always up-converted the 16 bit source before mixing, both for the reasons mentioned above, as well as that summing of the sources and any digital sample processing (eq, gain adj, etc.) will be more accurate in the 24 bit realm.  As dithering and/or resampling the mix back down to 16/44.1 may add some quantitization errors and aliasing, I see a reason to produce and archive a 24 bit version of the mix.

[Lil Kim Jong-Il]

I would use the highest resolution recorder for the source that is intended to dominate the mix.   For example if the matrix mix going to be 60% aud and 40% sbd, I'd use the 24-bit recorder for the aud tracks.

For a mix 50/50, I'd use the higher resolution recorder for the source that has the lowest self noise.

If I were making a 5.1 surround mix, then 24-bit for the main tracks and 16-bit for the surround tracks.

[tbrown4]

Thanks for all the feedback, folks.