bit conversion

edit : bit conversion. i was messin with some kits tryin to get a gritty old skool sound by converting the bits and sample freq, and had questions maybe some DSP heads around here can answer?

does anybody know how you can do bit/ sample rate conversion and still end up with a 16bit/44.1 file? i expect that dropping some LSB bits off and just stuffing zeros back on would give the sound while leaving the bit rate readable by the os...but i'm wondering about the sample rate convert..anybody know whats up?

cheers!

isn't the bit rate of the sample always going to be the same, since the 2500/1000 is 16 bit? when you convert, isn't it just say 12 bit 'emulation'?

can you take a high resolution photograph of a low resolution photograph of a high resolution photograph?

I think the better question to ask is what do you get if you do that... a good rule of thumb is the lowest common denominator which in this case would be the low res photograph, but that doesn't account for artifacts and other possible issues incurred during the process.

To answer the OP... JJOS will convert a sample to many different bit rates/frequency bands. In memory the file is still 16bit/44.1k. Bit conversion from 16bit to 8bit is pretty transparent as it is a multiple of the expressed volume level of the sound in 16bit, nothing too magical there. 16bit to 12bit doesn't fair quite so well since the numbers cannot be converted 100%, but it is pretty close. The 44.1khz to 22khz also fairs somewhat well since it is a multiple of the 44.1khz, but since you are playing the converted "22khz" file through a 44.1khz sound engine it won't sound exactly the same as a 22khz sound engine.

Personally I'd say that the JJOS bit/khz conversion is a fair substitute for the sample conversion rates you'd like, but it isn't perfect. It's kind of like a kit car... you'll probably fool most of the people into thinking you've got a porsche, but under the hood you're still running a VW Bug. A lot of the magic that comes from sampling on older hardware also comes from the tune/pitch shifting side as well, and the MPC 1k/2.5k just can't reproduce the artifacts inherent to those older sampling engines since the 1k/2.5k work at a higher frequency and thus produce fewer artifacts.

YES!

just buy an old 12 bit echo pedal for a guitar and sample through it 100% wet and with the feedback turned off...

hes right about old pitching algorithms. but analog filters have something to do with the old sound too.

yeah thanks for the replies all...was just wonderin what people thought about it..i used to have an sp1200 waay back...and its those artifacts when you change the playback pitch that really stand out..

While this topic is up here... Does anyone agree that the bit/frequency conversion sounds pretty lame? I'm a big fan of crunchy sounding lower bit rates, but this function doesn't sound cool, let alone authentic to me.

If it works for you, what settings did you use? And in what context?

elevated wrote:While this topic is up here... Does anyone agree that the bit/frequency conversion sounds pretty lame? I'm a big fan of crunchy sounding lower bit rates, but this function doesn't sound cool, let alone authentic to me.

If it works for you, what settings did you use? And in what context?

Only on some snares and even fewer kicks.

elevated wrote:While this topic is up here... Does anyone agree that the bit/frequency conversion sounds pretty lame? I'm a big fan of crunchy sounding lower bit rates, but this function doesn't sound cool, let alone authentic to me.

If it works for you, what settings did you use? And in what context?

Some percussion... I've found it reasonable on sounds that have some decent low pitch. Higher pitch sounds in my opinion don't fair so well. I'd push a kick/bass drum through it and see if it sounds better, but strings don't sound so great in my mind.

If you want real lofi sounds you really need to get the real gear. Again, you can fake it if you know what is going on under the hood and can find a good matching effect, but that's pretty tough too.

What about the computer plug-ins just for doing this effect? Can anyone compare?

don't forget the 'BIT GRUNGER' effect in the FX section.

all realtime, no conversion necessary. it's limited but i've gotten some cool sounds out of it.

for anyone interested in how the bit convert compares:

http://www.mikefeedback.com/MPC2500/Com ... 1025Hz.WAV
http://www.mikefeedback.com/MPC2500/Com ... 2050Hz.WAV
http://www.mikefeedback.com/MPC2500/Com ... 4100Hz.WAV
http://www.mikefeedback.com/MPC2500/Com ... 4100Hz.WAV
http://www.mikefeedback.com/MPC2500/Com ... 1025Hz.WAV
http://www.mikefeedback.com/MPC2500/Com ... 9200Hz.WAV

rich_biatch wrote:YES!

just buy an old 12 bit echo pedal for a guitar and sample through it 100% wet and with the feedback turned off...

hes right about old pitching algorithms. but analog filters have something to do with the old sound too.

great idea! try running your samples thru a tube amp and any old distortion pedal with a nice clean boost , eq the hell out of it and you should get enough gritty to make a 900 pound cheesehead sh** out a gravy river.

Sooty_G wrote:don't forget the 'BIT GRUNGER' effect in the FX section.

all realtime, no conversion necessary. it's limited but i've gotten some cool sounds out of it.

yeah i put that on everything but cymbals..LOL!

Mike Feedback wrote:for anyone interested in how the bit convert compares:
...

Thanks for these files, Mike,

I didn't expect the differences to be that tremendous. Tested on two speaker/amp
setups I clearly state the S950 examples to sound more musical and punchier than the
12bit JJ gimmick. Especially the snaredrum really shines through. Maybe this is due
to a non-linearity in frequency-response, but I am not sure about this.

TSR