Taperssection.com

Gear / Technical Help => Ask The Tapers => Topic started by: piperedworm on August 10, 2010, 10:50:24 AM

Title: Just Curious . . . Why Re-Sample
Post by: piperedworm on August 10, 2010, 10:50:24 AM
Hello my friends

Just curious, I record everything in 24/48.  If I am not going to be ripping CD's . . . Why Re-Sample to 16/441?

Is there some advantage to doing this?

Sorry if this is a stupid question

Jeff
Title: Re: Just Curious . . . Why Re-Sample
Post by: page on August 10, 2010, 10:58:25 AM
Hello my friends

Just curious, I record everything in 24/48.  If I am not going to be ripping CD's . . . Why Re-Sample to 16/441?

Is there some advantage to doing this?

As long as you have the space and equipment that will handle 48khz files where ever you want to use them, I don't see that you gain anything by resampling down to 44.1. If you listen to stuff in your car and the stereo system you have won't do 48khz, that would be an example where resampling would come into play, but otherwise I'm pressed...
Title: Re: Just Curious . . . Why Re-Sample
Post by: piperedworm on August 10, 2010, 11:03:05 AM
For the car I usually take the 24 48's and rip them into 320kbs MP3's and throw them on my IPOD (I know  . . . ughh MP3's)

Title: Re: Just Curious . . . Why Re-Sample
Post by: Fatah Ruark (aka MIKE B) on August 10, 2010, 11:05:40 AM
Only 1 reason for me: Sharing via Bit Torrent for people that don't want/need 24 Bit.

I listen to my recordings in 2 ways. At home I listen to the 24 Bit source via my media server. In the car I listen to V0 MP3's because my car plays MP3's (but not FLAC).

RE: MP3's in the car. I don't see ANY reason to listen to 24 Bit in the car (if it's moving). First of all not many of us (including me) have super high end systems in the car, and most importantly...road noise.

I don't ever listen to the 16 Bit FLAC's, although I do keep them archived.
Title: Re: Just Curious . . . Why Re-Sample
Post by: page on August 10, 2010, 11:25:34 AM
Only 1 reason for me: Sharing via Bit Torrent for people that don't want/need 24 Bit.

I listen to my recordings in 2 ways. At home I listen to the 24 Bit source via my media server. In the car I listen to V0 MP3's because my car plays MP3's (but not FLAC).

RE: MP3's in the car. I don't see ANY reason to listen to 24 Bit in the car (if it's moving). First of all not many of us (including me) have super high end systems in the car, and most importantly...road noise.

I don't ever listen to the 16 Bit FLAC's, although I do keep them archived.

yeah, it's all about what's the goal/need. For my portable, I'll do highbitrate ogg files (cause it's gapless and smaller), and at home, I've got 16bit flacs. Since I keep the raw recording (in 24bit), and I can't hear a difference, I don't see a reason to burn the space for 2 24bit sets compared o 1 24bit and 1 16bit.

I also share the 16bit files so I have a dual reason, but if you don't, then it's back to the hardware requirements.
Title: Re: Just Curious . . . Why Re-Sample
Post by: SmokinJoe on August 10, 2010, 12:21:46 PM
The biggest reason I can think of (and the reason I do) is because I want to make it easy for the people I share my music with to enjoy it without having to jump through hoops.  Most downloaders barely know how to get bittorrent to work, let alone doing the dither/resample so they can burn CDs.
Title: Re: Just Curious . . . Why Re-Sample
Post by: acidjack on August 10, 2010, 02:49:21 PM
Yeah, 16/44.1 mostly just satisfies downloaders who'll bitch at you.  I usually record at 24/44.1 because I'm not worried about syncing to video and don't care about the extra bits, and figure the downsampling will be "easier" on the computer.  But eventually, I suspect I will stop doing it, mostly because I don't care about the CD format.

Title: Re: Just Curious . . . Why Re-Sample
Post by: fmaderjr on August 10, 2010, 03:23:58 PM
Just curious, I record everything in 24/48.  If I am not going to be ripping CD's . . . Why Re-Sample to 16/441?

Is there some advantage to doing this?

No advantage if you are not going to burn to CD. No reason to re-sample.
Title: Re: Just Curious . . . Why Re-Sample
Post by: stevetoney on August 10, 2010, 03:54:19 PM
For bands that are on LMA, I upload both 24/48 and 16/44.1 versions as a courtesy to people so they can pick which they want.  On average, I'd estimate that downloaders pick my 16/44.1 versions with about 2 to 3 times the frequency as the 24/48.  It's interesting though that I've seeded some shows where the 24/48 version has more downloads than the 16/44.1. 

For archiving purposes, after I share the 16/44.1 version, I get rid of it and I only keep the 24/48 version.  If I were living only for myself, I have no need for 16/44.1 anymore.
Title: Re: Just Curious . . . Why Re-Sample
Post by: SmokinJoe on August 11, 2010, 12:39:15 PM
For bands that are on LMA, I upload both 24/48 and 16/44.1 versions as a courtesy to people so they can pick which they want.  On average, I'd estimate that downloaders pick my 16/44.1 versions with about 2 to 3 times the frequency as the 24/48.  It's interesting though that I've seeded some shows where the 24/48 version has more downloads than the 16/44.1. 

I've got a theory that 60% of the "downloads" we see on the LMA are streams.  Then 30% of the people download one or more MP3s, and only 10% download flac files.  The extension of this theory is when you see more downloads on the 24bit source, it's because more people are streaming or downloading mp3s, and most of them don't know or care what "24 bit" means.

If anyone ever sees real figures about this, please post.

Title: Re: Just Curious . . . Why Re-Sample
Post by: rastasean on August 11, 2010, 01:54:19 PM
yeah, ONE single play counts as a full download on the 16 bit. you can't stream 24 bit so unless people are really into getting 24 bit, the majority will just download mp3s. I was recently downloading FLACs with downloadthemall but that plugin doesn't work in firefox beta and I don't really care to start each FLAC download manually.

I think uploading 16 bit FLAC to LAM is a good idea so it can be streamed. Nothing is worse than downloading a 24 bit show which, for one reason or another, sucks.
Title: Re: Just Curious . . . Why Re-Sample
Post by: rastasean on August 15, 2010, 11:18:49 PM
so if you download a 24 bit recording, how do you downsample all songs to 16bit? My music player can't play 24 bit files unfortunately.
Title: Re: Just Curious . . . Why Re-Sample
Post by: twatts (pants are so over-rated...) on August 15, 2010, 11:25:31 PM
The biggest reason I can think of (and the reason I do) is because I want to make it easy for the people I share my music with to enjoy it without having to jump through hoops.  Most downloaders barely know how to get bittorrent to work, let alone doing the dither/resample so they can burn CDs.

What he said...

Pretty much, I do it for other people...

Terry
Title: Re: Just Curious . . . Why Re-Sample
Post by: twatts (pants are so over-rated...) on August 15, 2010, 11:27:42 PM
For the car I usually take the 24 48's and rip them into 320kbs MP3's and throw them on my IPOD (I know  . . . ughh MP3's)

This is what I do... 

Its so easy, why would you not do it???  And with road-noise, who can tell the difference???

Terry
Title: Re: Just Curious . . . Why Re-Sample
Post by: Brennan on August 16, 2010, 02:14:50 AM
The biggest reason I can think of (and the reason I do) is because I want to make it easy for the people I share my music with to enjoy it without having to jump through hoops.  Most downloaders barely know how to get bittorrent to work, let alone doing the dither/resample so they can burn CDs.

What he said...

Pretty much, I do it for other people...

Terry

^^^
What they said...for others to download and easily listen to / burn.
Title: Re: Just Curious . . . Why Re-Sample
Post by: SmokinJoe on August 16, 2010, 12:05:04 PM
yeah, ONE single play counts as a full download on the 16 bit. you can't stream 24 bit so unless people are really into getting 24 bit, the majority will just download mp3s.

I'm not exactly saying you can stream 24bit... I'm saying 24 bit files are used to derive MP3s which are streamable if you allow them to be derived.  I assume if people stream this it generates hits on the download counter for the 24 bit source, and if more people stream this source than the 16bit source, it might make the 24bit source look more popular. Here is an example:
http://www.archive.org/details/rmb2010-02-26.akg414-sbd-mix.flac24f  has 101 hits at this moment
http://www.archive.org/details/rmb2010-02-26.akg414-sbd-mix.flac16f  has 150 hits at this moment.

I put the 24bit source there for those who want it, but I don't think 101 people really download 24 bit flac files for high end audiophile systems.  I think most of them streamed it, or grabbed MP3s for an iPod, and most don't know the difference between 16 bit and 24 bit.  The 16bit source has more hits primarily because it went up a few days earlier.  After that it's 5050 at random.
Title: Re: Just Curious . . . Why Re-Sample
Post by: disco on August 17, 2010, 02:16:37 PM
so if sample size doesn't really affect much if you record at 48 and convert to 44, does bit depth conversion yield anything better....since the 48>44 doesn't offer anything better, does going from a 24 bit tape to a 16 tape yield any better results?
 I record everything in 24/48 but usually just archive my 24 bit wavs, seed the 16bit flacs and archive a set of the flacs as well. Am I wasting my time/space by recording in 24/48 or is
it just a good practice to record at the highest bit rate/sample available so that you have the best possible pull?
Title: Re: Just Curious . . . Why Re-Sample
Post by: page on August 17, 2010, 02:32:23 PM
so if sample size doesn't really affect much if you record at 48 and convert to 44, does bit depth conversion yield anything better....since the 48>44 doesn't offer anything better, does going from a 24 bit tape to a 16 tape yield any better results?
 I record everything in 24/48 but usually just archive my 24 bit wavs, seed the 16bit flacs and archive a set of the flacs as well. Am I wasting my time/space by recording in 24/48 or is
it just a good practice to record at the highest bit rate/sample available so that you have the best possible pull?

for recording, 24bit over 16bit yeilds much better bang/buck then higher sample rates (baring some special thing you are recording like bats). 24 bit puts the bottom bit around -144db (realistically somewhere around -120db) while 16bit's hard maximum is -96db. So what this means is that if you are recording with 16bit and amplify it, you are bringing up the noise floor from 96 while your (mechanical) noise floor ** is probably lower on the 24bit file. As such, running your levels lower and amplifying in post production doesn't have nearly the downside with 24bit recording then it does with 16bit recording.

http://en.wikipedia.org/wiki/Audio_bit_depth

** This doesn't include the noise floor of whatever soundstage you are trying to capture. A crowded bar's "noise floor" is most likely well above -96db, and you microphones noise floor is probably above the -96db threshold as well. What this does is allows you to back off of your gain to prevent clipping without taking a hit on the noise when amplifying it later.
Title: Re: Just Curious . . . Why Re-Sample
Post by: disco on August 18, 2010, 01:01:13 AM
so if sample size doesn't really affect much if you record at 48 and convert to 44, does bit depth conversion yield anything better....since the 48>44 doesn't offer anything better, does going from a 24 bit tape to a 16 tape yield any better results?
 I record everything in 24/48 but usually just archive my 24 bit wavs, seed the 16bit flacs and archive a set of the flacs as well. Am I wasting my time/space by recording in 24/48 or is
it just a good practice to record at the highest bit rate/sample available so that you have the best possible pull?

for recording, 24bit over 16bit yeilds much better bang/buck then higher sample rates (baring some special thing you are recording like bats). 24 bit puts the bottom bit around -144db (realistically somewhere around -120db) while 16bit's hard maximum is -96db. So what this means is that if you are recording with 16bit and amplify it, you are bringing up the noise floor from 96 while your (mechanical) noise floor ** is probably lower on the 24bit file. As such, running your levels lower and amplifying in post production doesn't have nearly the downside with 24bit recording then it does with 16bit recording.

http://en.wikipedia.org/wiki/Audio_bit_depth

** This doesn't include the noise floor of whatever soundstage you are trying to capture. A crowded bar's "noise floor" is most likely well above -96db, and you microphones noise floor is probably above the -96db threshold as well. What this does is allows you to back off of your gain to prevent clipping without taking a hit on the noise when amplifying it later.

thanks for the info & linky
Title: Re: Just Curious . . . Why Re-Sample
Post by: Shadow_7 on August 18, 2010, 07:52:08 PM
Some things I've noticed.

The MP3 encoder will resample your audio to 16/44.1 before it does it's things.  Who do you trust to do a better job of it, the MP3 software or some other software?  A higher quality input almost always gives a higher quality output.  Even when it comes to MP3.

When I do a high quality (slow) resample from a higher bitrate, it seems to have a significant impact on the noise floor of the recording.  But I'm also resampling to sync up two unrelated devices.

Some effects are only available at 16/44.1.  Depending on the software being used.  sox + earwax

Otherwise always keep the highest quality originals.  If only for archival purposes.
Title: Re: Just Curious . . . Why Re-Sample
Post by: page on August 18, 2010, 09:45:00 PM
Some things I've noticed.

The MP3 encoder will resample your audio to 16/44.1 before it does it's things.  Who do you trust to do a better job of it, the MP3 software or some other software?  A higher quality input almost always gives a higher quality output.  Even when it comes to MP3.

You bring up a good point, do you trust your MP3 software to do the resample/dither or the outboard software elsewhere? Doesn't change the retention question, but does give pause for considering your workflow.
Title: Re: Just Curious . . . Why Re-Sample
Post by: piperedworm on August 19, 2010, 08:51:38 AM
That is kind of funny - Taperj and I were just talking about this last night.  I am going to do the "Pepsi Challenge" (yes I am showing my age here) tonight.

Re-sample one track then convert to 320kbs Mp3 and listen to the same track that I coverted to Mp3 straight from the 24/48 source.

Again, these are usually for the car/Ipod or for my friends that have no clue what 24/48 even means let alone what to do with it . . . but none the less now I am curious.

Title: Re: Just Curious . . . Why Re-Sample
Post by: Todd R on August 20, 2010, 11:32:18 AM
The MP3 encoder will resample your audio to 16/44.1 before it does it's things. 


Wondering where you got this from?  Is this down-sampling to 16/44.1k before mp3 encoding specific to the encoder you use and is this pre-encoding downsampling discussed on the manual for the encoder or something?

If that is indeed how it works (and just for some encoders or all?), I agree, it sounds like it would be best to do the downsampling yourself first with high quality audio software. I've tried to do a fair amount of investigation into this since I derive my own 320 kb/s from my 24bit files and I want to make sure I'm getting the best results I can.

Here is another discussion on the 24bit>mp3 thing:
http://taperssection.com/index.php?topic=136471.msg1779929#msg1779929

I never kept track of the various studies and technical discussions I found when I was researching, but at least the post above has links to the relevant mp3 standards.  The mp3 standard accepts 24bit inputs and it seems like a really dumb way of encoding to first down-sample to 16bits when it doesn't seem at all necessary.

I'm not trying to bag on you at all, just trying to get to the bottom of things, but I'd like to know if you have solid information that your mp3 encoder or all mp3 encoders downsample to 16bits before encoding or if you are just assuming that that is how it works.  I've never seen that mentioned in the technical stuff I was able to dig up, and it seems totally at odds with the mp3 standard.
Title: Re: Just Curious . . . Why Re-Sample
Post by: Shadow_7 on August 21, 2010, 10:52:39 AM
The MP3 encoder will resample your audio to 16/44.1 before it does it's things. 


Wondering where you got this from?  Is this down-sampling to 16/44.1k before mp3 encoding specific to the encoder you use and is this pre-encoding downsampling discussed on the manual for the encoder or something?


It might be lame specific.  But I read it in the documentation for that (or of that) encoder which seems popular as the goto MP3 encoder.  It also makes sense in that MP3 is optimized for CD quality.  Not to imply that ALL encoders do the resample first step.  Or that the codec itself is CD quality specific.

lame/USAGE

--- low bitrates ---
lame will automatically convert to 16 bit (as will FhG and Xing)
(slightly paraphrased)

--- CRC error protection ---
Yes this really does work correctly in LAME.  However it takes 16 bits per frame that would otherwise be used for encoding.

--- sampling frequency in kHz ---
LAME will automatically resample the input file to one of the supported MP3 samplerates if necessary.

lots of references to "The input file can be any input type supported by encoding", but no list of encoding supports directly...  Without delving into the actual code anyway.  But it stands to reason that most of the bug reporting and fixes would be related to 16 bit 44.1kHz samples (CD quality).  So even if the other rates are supported, there may be unreported and unresolved issues related to content (if only in theory).  And on the manpage for frequency options the list 8/11.025/12/16/22.05/24/32/44.1/48 is listed.  Which would imply that 24 bit 96kHz is NOT a supported encoding

under "-b n" in the man page.
- For MPEG-1 (sampling frequencies of 32, 44.1 and 48 kHz)
- For MPEG-2 (sampling frequencies of 16, 22.05, and 24 kHz)
- For MPEG-2.5 (sampling frequencies of 8,11.025, and 12 kHz)
(with a list of n values for each)

Mpeg-1 Layer III for what passes as a playable MP3 on my MR-1000 field recorder.  (stereo ONLY, if the latest firmware hasn't addressed that quirk on that device)
Title: Re: Just Curious . . . Why Re-Sample
Post by: Todd R on August 21, 2010, 03:23:39 PM
Thanks Shadow for passing that info along.  It'd be great to get a clear answer, maybe more digging will uncover it.  Not sure though from what you posted that it would down-sample 24bit to 16bit.  The passage about automatically converting is stated for low bit-rates, which I'm reading as it will upsample 8bit or 12bit material up to 16bit for the conversion, but not necessarily that it would down-convert 24bit to 16bit.  Which makes sense as the mp3 standard seems to be defined for 16 and 24 bit inputs.

Not sure what it is getting at with the CRC correction, but on the sampling frequencies, from the standard I would expect that re-sampling to 32/44.1/48 would happen as those seem again to be the frequencies that the mp3 standard supports.  And yes, I would definitely expect since 96k (and anything other than 32/44/48) would be re-sampled as the mp3 standard doesn't make allowances for them. 

Still though, even from what you've posted, I'm hopeful that material that is recorded at 16/48, 24/44 and 24/48 would be converted to mp3 directly -- meets the input standard for mp3, and from my reading of what you posted, it doesn't seem that LAME is saying otherwise.

[fingers crossed]
Title: Re: Just Curious . . . Why Re-Sample
Post by: Shadow_7 on August 21, 2010, 06:48:58 PM
The hint that it specifically resamples to 16/44.1 might be a ffmpeg quirk.  But that's more for video.  I do remember reading specifically that 16/44.1 was the standardized input to a specific MP3 output.  And adjusted most of my routines to preconvert as much as possible.  But I'll have to research that harder.  And that info might have been in error to start with.  Or perhaps related to how things worked two or more years ago.
Title: Re: Just Curious . . . Why Re-Sample
Post by: lastubbe on August 22, 2010, 11:29:51 AM
I was brought up as a young tape trader (15/16 years old) in the spirit of sharing and trading.  That's how I got into this, and that's how I've always been.

The spirit of the music, and the concept of taping live shows, is to spread and share.  If someone didn't share with me, I may not have ever had the pleasure of the being introduced to the music I follow and collect today.

It makes no sense to me why tapers would not want to share. (another topic)

With that said, it is still 2010, and 16/44.1 is still the commonly used format, as most listeners use iPod and CD.  Since I use a high resolution recorder, it is necessary for me to resample for people to be able to take advantage of the shows I share.

Now a High Resolution iPod would be cool.  You know that's coming!

HDTV.  HDIPOD.
Title: Re: Just Curious . . . Why Re-Sample
Post by: newplanet7 on August 22, 2010, 03:59:04 PM
 :cheers:
Well put sir.