well, yes and no...........in no particular order.........

gonk: are you hosting the file?

Otherwise, where can I get it?

BTW, this CD on SACD is one of my favorite demo SACD discs....

I can host it as well. As soon as I get the CD, I'll pull an image and post it for those that want to grab it and burn their own. I'll make myself a copy and send the CD on to the next person that wants it.


brianca

Great! The song is about 9 minutes long or thereabouts, so the file will be pushing 95MB - but I hope you can do it.

I just addressed the CD for you, and will be taking it to the Post Office tomorrow morning.

I've started clearing some room for the file, and will host it when I get my copy of the CD. I'll stick a link to it here when I get the file up.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

Great! I mailed the CD this afternoon.

Although this is an interesting exercise, it really isn't the same as comparing digital audio at different bit depths. 24 bit records don't just add 8 more bits below the current 16.

By truncating the least significant bits, your are cutting information out, but only certain parts -- the quiter parts. A true 12 bit recording doesn't totally lose some of the sound, it just has effectively less resolution across the entire sample. So, by taking a 16 bit recording and truncating the bottom 4 bits, you are keeping ALL of the resolution contained in the most significant bits. Take a single piano note, struck loudly. By truncating bits, the beginning will likely sound identical, but the 'fade' will stop suddenly once it reaches a certain level. If the entire note was done at 12 bits from scratch, you wouldn't get that sudden crop, but rather less resolution in the dropping sound levels.

Think of a still image, with 24 bits per pixel (8 bits each for RGB), then truncate 6 bits off to make an 18 bit per pixel image. If the original image consisted of only very bright pixels (narrow dynamic range), you probably couldn't tell the difference. If the image instead had a very broad dynamic range (bright sky fading to a dark horizon), you would lose fainter details. If the image were resampled to an 18 bit depth, instead of simply cropping, some of those lost details would be retained, at the expense of banding as the sky faded.

Stereophile magazine had a good CD out a few years ago for TRUE comparisons of recordings at different bit depths, called Testmasters. They recorded a solo piano along multiple paths at the same time. Same performance, same microphones, same levels. Along some paths, analog mastering was used. Various digital paths were used, including straight 16 bit, 24 bit with dithering, various dithering techniques, etc, HDCD, and so on. It's easy to compare each technique by skipping tracks around.

It is also easy to tell the difference between straight PCM and 24 bit dithered down to 16 bits -- not to mention the differences that would most likely be evident if the experiment were re-created today with a medium like DVD-A, which would allow true 24 bit recording to be directly compared.

Bigmac:

Read my 3rd post above. I didn't just throw away the lower bits - it was done the proper way with professional mastering software and a ProTools digital audio workstation, by taking the lower bits of the original file and folding them into the lower bits of the new file during a direct digital bounce to hard disc. Noise shaped dither was added at the same time at the appropriate bit depth. Trust me, I work with digital audio daily (yes, including 24 bits, multichannel) as a Music Editor for motion pictures, and I know what I'm doing. This IS a valid test. I don't have any particular agenda here, other than to give people who wouldn't have an opportunity otherwise to hear what these lower bit resolutions sound like, and maybe they'll have a little fun in the process. Why don't you keep an open mind and download the file when it becomes available, or get it from one of the people I have sent it to when they are finished with it.

I didnt mention on my original post that this track is just part of an entire CD I made, containing a variety of material, and YES, I made ORIGINAL 16, 12 and 8 bit recordings of a piano for the CD. And yes, I made 24 bit ones also, as my workstation is capable of 24 bit resolution. I simply made the Miles Davis available because it is widely recognized as an audiophile favorite demo piece that many people already posess, so they can compare.

[This message has been edited by soundhound (edited October 10, 2002).]

I see bigmac's point that if the 4 (or 8) lsbs were simply tossed away (truncated), that would not the same as orignially recording at 12 (or 8) bits.

To illustrate this, say you have two tones. One tone is large in amplitude, consuning a large percentage of the recording medium's dynamic range. The other tone is small, by itself consuming less than the range of 4 (or 8) bits, the number of bits you are later going to truncate. If you record the big tone only, then both tones together, and then the small tone alone, then simply throw away (THIS is truncation) the least significant 4 (or 8 bits), the playback result will have the large tone in the part where just the large tone was recorded (with distortion due to the truncation), the region recorded with both tones will have both tones (with distortion due to the truncation) but the region recorded with the small tone alone (which had a recorded amplitude less than the number of bits that was truncated) now has nothing.

In soundhound's orignal post in this thread, he said he truncated the least 4 or 8 bits. From what he said later, it sounds as though he did not actually truncate (chop off). Beings I am not a recording engineer, I do now know what procedure or process would be used to go from 16 bits to 12 or 8 in a non-truncating way. Of course converting back to analog and then re-digitizing with a 12 or 8 bits word length would do the trick. I have no doubt that there is a digital process that can take one from 16 bit word space to 12 or 8 bit word space(without truncation) without going through the intermediate analog state.

I remember years ago when I purchased my first computer sound card (a Turtle Beach Monterey, with I stil have but don't use because it is ISA and non-plug and play). I played aroung with recording, via the line input, various snippets of sound from an audio CD player. I recorded in 16 bits and 8 bits and compared the two. I was shocked at how good (compared to my expectations) the 8 bit recording sounded. I was expecting the 8 bit recording to sound much worse that it did.

So, when soundhound says that he has propely went from 16 bits to 12 or 8 (non-truncating), I suspect that it will be not as easy as we might think to tell (by listening only) which section of music was recorded with how many bits.

Paul

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the 1derful1

[This message has been edited by Paul J. Stiles (edited October 10, 2002).]

Geez, I'm sorry I used the word 'truncate' in my first post!! I have since corrected it. (-: I explained this further 3 posts later. You are quite correct that if I _did_ simply chop off the lower bits, I would be throwing away valid information in the original file. The way I did do it in essence 're-recorded' the original file digitally (but with _no_ A/D or D/A conversions taking place) at the new bit depth as a new file, while adding dither.

I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.
I will _not_ say "truncate" again.

(-:


[This message has been edited by soundhound (edited October 10, 2002).]