Does anyone know what range you should aim to keep the audio level bars between on the Canon XH A1?

For instance if you are recording a normal conversation what should be the minimum number of bars you want to see for quiet speech and what is the maximum number of bars you want for the loudest speech?

And what should be the maximum number of bars for very loud sounds like shouting, gunshots or a glass smashing?

The reason I ask is that I don't want to have distorted loud sounds or to have to boost the volume in post-production on quiet sounds and pick up background hum.

Thanks!

Audio levels need to be adjusted to make the most of the sound information, whether loud or soft. Try to make the level meters peak without lighting the last (right-most) segment. You can't just set them and forget them. As with everything, it depends on what you are shooting and what sort of a crew you have.

As discussed in this thread (http://www.dvinfo.net/conf/canon-xh-series-hdv-camcorders/129434-xh-a1-audio-question.html), adjusting the XH-A1 audio level controls while shooting is too fiddly to be practical. If you are shooting on a well-controlled set, you can re-adjust the levels during the rehearsal of each scene. However, if you are running and gunning, so-to-speak, you have three choices:
1) Use Auto. As these things go, the XH-A1 ALC is not bad, and it's the safe option. This is what I usually do. In noisy environments, such as a factory or a busy city street, try switching in the MIC ATT, too. However, it's usually possible to improve on what ALC gives you (as with most Auto functions), provided you've got enough hands!
2) Feed one mic into both channels and set different manual levels on each, one for "normal" sound, the other for loud sound. In post, use the "normal" one unless it's distorted, and hope the "loud" track is OK throughout. You'll still have to keep a careful eye on the levels and adjust as you go along, but at least you have a bit of a safety net. (This will work with the internal mics too, so long as the source is more-or-less in front of you.)
3) Get a mixer with limiters, which attenuate loud sounds, like ALC, but without boosting things when it's quiet. The SD302, which is a proper portable mixer with a lot more to offer than just limiters, seems to be the bees knees, but it's not cheap. Somewhere I've seen a smaller gadget that bolts under the camera, possibly a version of the famous "Beechtech" box, that provides in-line limiters between the mic and your camera. This only works with external mics.

The position of your mic relative to your subject can make a huge difference to your levels, as well as to the quality of the sound (reverb, etc.) If you hear things distorting, take a couple of steps away. If it's too quiet, get in closer (consider using a lapel mic?)

The "pro" solution is to hire a sound operator, with a boom, mixer and headphones, but good ones are not cheap.

One last thing - wear headphones, preferably good ones that will let you hear when the audio starts to distort, so that you can shout "cut", or at least adjust the dials a bit.

BTW I'm no expert. This is basically advice I've picked up from the DVi audio forum and similar places. As I say, because I work by myself 99% of the time, I stick to ALC. I always use headphones, though, just to be sure.

Good info. I think Stuart was asking about specific levels. I try to keep voices between a -20 and -12, letting things peak up to about a -6. With most DV/DVCAM cameras I used in the past, I never peaked over about a -10, but this one seems to have more latitude. For really loud sounds, like applause. car horns, etc., you could probably let them peak at close to zero. The meter in the VF only gives you bars and a little green dot at -12; check the side readout for real numbers.

Thanks Mark and Bill. That's just what I needed.

Bill: I didn't realise there were audio levels on the side panel readout, I haven't really looked at it before. I'll look when I get home.

Is zero where the red bar is on the viewfinder monitor?

Mark: I have someone doing sound, but they are not trained. But we will have time to do audio tests before filming so I'll do it that way and adjust gain with the wheel on the camera. We don't have a mixer I'm afraid, can't really afford one, but we do have some good headphones at least to listen for distortion.

I notice the levels you suggest are very different to those I have been suggested to use in Adobe Premiere with speech between -6 and -3 db, background music at -18 to -12.

You can find this info in the following thread:

http://www.dvinfo.net//conf/showthread.php?p=930848#post930848

Is this just because the Premiere and XH A1 audio volume scales are different?

I didn't know the dots on the XH A1 audio level meter correspond to the units on the side display panel. Thanks for that Bill. Now I know what each dot signifies it will be easy to monitor the audio and get the levels right!

One caveat about using ALC on two different sources. The A1's ALC will tie both channels together somewhat. By that I mean a very loud input from one channel will drive down the audio on the other. I know this from experience.

I tried ALC once whilst shooting races. Track announcer on CH1 and race ambient on CH2. Worked OK when the little 4 pots were running, but when the big V8s came out, it lowered the announcer volume when the engines got loud.

Not saying your shouldn't use it, but you might want to test it out in your conditions before you commit to it.

The ground idea is always to record as loud as possible. -6dB uses only a half of the possible dynamic range (this is logarithmic scale) and resolution of 16 bit. -12db only a quarter of them.
There ist always a quantisation noise and noise from mic preamp etc. It is important to record with highest amplitude to have a greater difference to noise amplitudes.
So if you record voice to 0dB - ist qauntizated always to one of the 65535 levels of 16bit resolution.
If you record the some voice to -12dB - you use only a quarter of the amplitude an you have only 16383 levels of quantisation.
Due to this uses recordings studios 24bit resolution. To have enough resolution with lower audio levels and bigger precision with postproduction.

Thanks Ivan. You've explained that very well. I had no idea you lost audio resolution at lower volumes. So basically you need a high signal to noise ratio. Will try to record as loud as I can without hitting the dreaded red -0 dB!

Make sure you listen carefully for distortion going that high.

Will do.

Cheers Bill.

Those are a lot of great reasons to use a 24 bit digital audio recorder with a limiter.

But the XHs usually work just fine. If Canon just incorporated a really good limiter, it would really be great.

Those are a lot of great reasons to use a 24 bit digital audio recorder with a limiter.

With 24 bit recording you have a lot of reserve of dynamic range - compare to 65536 levels of 16bit - there is over 16,7 millions of quantisation levels by 24 bit. You don`t really need a limiter for recording. Recording "safely" to -12dB in 24bit makes still better quality as 16bit at maximum level.

24 bit sounds like the way to go. Will think about getting a 24 bit audio recorder for the next film. I guess they are rather expensive?

What do they record onto? Hard drives?

24 bit sounds like the way to go. Will think about getting a 24 bit audio recorder for the next film. I guess they are rather expensive?

What do they record onto? Hard drives?
Hi Stuart
I use a Fostex FR2 LE which isn't ridiculously expensive for what it is - about £360. It records to standard flash cards (but you need to get one that's on their recommended list).
If you decide to go down this route it may be worth buying a Tamiya battery (from a model shop - used for toy cars etc) and charger and 8GB flash card. That adds a lot to the cost (another £120 or so I think) but it means that the recorder will run for 8 hours without charging or changing the media. That's what I did.
I used it to record a double bass at close range - a notoriously difficult thing to do according to the engineer at Fostex because the lower frequencies are massive - and got a slightly muffled result.
However I got a sound engineer to look at it he pulled the rabbit out of the hat and produced an excellent end product.
I think he could do this because I recorded 24 bit.
The only fly in the ointment is that Jay Rose in his excellent book 'Producing Great Sound for Film and Video' refers vaguely to thousand dollar units by Tascam and Fostex and says 'These prosumer units have fewer features; and while they boast 24-bit recording, our measurements have shown this mode to sound about the same as 16-bit when you use their analogue inputs'.
(expletive deleted) marvelous.
It's a minefield buying sound kit. It's so technical and so much jargon and so much of what you read is contradictory.
I buy what Ivan says above.
I hope Jay Rose is wrong (in this case he seems to be from my experience).
I've been meaning to post a thread about this and will now do so as it seems appropriate to start a new one rather than take this thread off at a tangent.

There is a lot of external USB an Firevire 24bit Soundcards to use with laptops.
For "portable" use i am working with little Behringer mixer with integrated Soundcard and CAD condenser Microphones.

Richard: Thanks for the input. I find all the audio stuff pretty inpenetrable too. Maybe Jay Rose works for a high end 24 bit recorder firm.

Ivan: So you record direct to a laptop Ivan? That sounds like a good idea, well, except that I don't have a laptop. Do you get good quality that way? Can you plug an XLR cable into the 24 bit soundcard? Are these cards recording genuine 24 bit audio? Would it be essential to have a mixer to record to a PC? I could always take my old desktop PC on set :| Sorry, that's a lot of questions!

Quality of the sound depend not from a thing that only record a digital data. A laptop works here as good as another recorder. With a good 24bit soundcard you have an excellent sound recorder. But you need microphone preamplifier with phantom power for condenser mic.
Behringer BCA 2000 ist a cheap mixer with mic preamps an integrated 24bit soundcard - but there are some smaler units there.
I am using it as a mobile soundstudio - most for recordings voice overs. I have 2 such units by my "artists" directly at they home for recordings small projects an sending it per email to me.
But by filming i am recording directly to the camera - of course by maximal possible level.

Thanks again Ivan for your excellent advice.

The Behringer BCA 2000 certainly looks impressive aand the price is only about 140 pounds in the UK. Do you know how big it is?

Do you get recording software with these units? Or what software would you recommend?

It is 330mm x 100mm x 300mm. You can use any software that recognize system Soundcard.
I am working (recording an editing) with Sound Forge.

The downside of cheap mixers, such as the Behringer, is the quality of the microphone preamps is often rather poor. This may be the reason that Jay Rose (an independant sound engineer with long experience of sound for movies and broadcasting, and generally a reliable source of advice) is rather scathing about domestic 24-bit recorders. To get good quality digital sound, you need a combination of a good mic, a good preamp (to make the most of the mic's signal) and a good analogue-to-digital (A-to-D) converter. Ideally, each componant should do no harm to your signal. Very often, the difference between cheap and expensive mixers or soundcards is the quality of the preamps and A-to-D converters. My guess is that you will only hear a difference from 24-bit recording (compared with the XH-A1's built-in audio) if your preamps and A-to-D converters are sufficiently good.

Of course, the law of diminishing returns applies here, just like anywhere else, and there's no point buying recording gear that's way more expensive than your camera and microphone. But don't skimp on it, either.

My guess is that you will only hear a difference from 24-bit recording (compared with the XH-A1's built-in audio) if your preamps and A-to-D converters are sufficiently good.
If you record directly to XHA1 with a enough reserve in level to avoid clipping - you have to increase Levels in postproduction. There is a big difference in soundquality between 16 bit and 24 bit recording after increasing volume from -12dB to 0dB.
BCA 2000 from Behringer is a plastic thing - but it has for the price excellent mic preams with (built in limiter an noise gate) and definitelly lower noise level as cheaper little Soundcraft mixers.
You can download here a little soundfile from unexpensive CAD GXL 2400 microphone on BCA 2000 recorded into Soundforge atfer normalising amplitudes to 0dB and downmix with the piano. Converted to 16bit and saved as mp3. And the voice still sounds great.
www.arkdelfina.neostrada.pl/behr.mp3

in all this discussion about sound level i figured was the best place to ask this question... i recently purchased an audio technica wireless lapel mic system. all batteries are new, ive adjusted the gain to max on the transmitter and on the receiver in hopes to get a good level to tape on an xlh1. on the camera i have selected the right mic output and even cranked my gain to max there as well. IM NOT GETTING MORE THEN 2 dots/bars when someone is yelling.

ive taken the same wireless system and plugged it into a dvx100. same result

i have also run this system directly into my pro tools board. (here is where it gets weird) the thing works perfectly there.

my question is.... why? im really confused. do i need another preamp?

PLEASE HELP!

thanks guys

My first guess would be maybe you had both cams selected to line level instead of mic level?

you are right! i was messing with it again after i posted. that was the case, apparently on an xlh1 there is a small lag between switching the inputs and i was just too impatient when i tried that last time.

thank you sir!

Glad you got it sorted out.

...
2) Feed one mic into both channels and set different manual levels on each, one for "normal" sound, the other for loud sound. In post, use the "normal" one unless it's distorted, and hope the "loud" track is OK throughout. You'll still have to keep a careful eye on the levels and adjust as you go along, but at least you have a bit of a safety net. (This will work with the internal mics too, so long as the source is more-or-less in front of you.)
...


Hi Mark,

great idea, I considered the same, but how can achieve that on the XHA1? As soon as you connect a mic to CH1 and select recording to CH1+CH2 you have the same audio level on both channels. Any secrets to achieve what you suggested?

THX
peppo

Hi Mark,

great idea, I considered the same, but how can achieve that on the XHA1? As soon as you connect a mic to CH1 and select recording to CH1+CH2 you have the same audio level on both channels. Any secrets to achieve what you suggested?

THX
peppo

Use a XLR Y cable

If I went down the recording to lap top route using a 24 bit soundcard as you suggested Ivan. Would it be best to sync the audio to the video footage using a clapper board?

Would the sync definitely work? In other words would my camera and the audio recorder definitely record at the same speed as if it was slightly different the sync would gradually drift out over a long scene.

Thanks!

Digital Equipments are synchronized in time with much higher frequency as needed to synchronize audio. Normally should there not be a problem.

Thanks Ivan! I'll try to sort out a 24-bit system for my next film. It was very kind of you to give me so much advice.

Just be aware that only fairly expensive recorders get anything out of 24 bits. Most if not all sub $2000 recorders have so much noise that 24 bits is not any better than 16 bits. The recorder does put out a 24 bit file, but tha extra 8 bits are just noise. Even the best recorders like SD7xx, Nagra, Cantar and Deva at 2500-20000 dollar price range have about 20 bit resolutions in reality.

XH-A1 has very good audio if fed from a good mixer. I have achieved over 90 dB S/N ratios with Sound Devices 302 mixer. That is about 25 dB better than analog Nagra recorders 20 years ago, which were the absolute top pro equipment at that time. But for some people getting 500 times more dynamic range is not enough?

I'm confused now :(

Audio is too complicated.

Is it still worth using a 24 bit recorder if it only gives you 20 bit really?

Or is it better to buy a mixer and plug it into the XH-A1?

At the moment I have my shotgun microphone plugged straight into the XH-A1 XLR socket.

1) Mic straight to Camera
Pro: cheap, simple, good quality (about 80 dB S/N)
Con: difficult to set levels on the fly, no limiter, only 2 mics maximum at one time

2) Mic(s)->mixer->camera
Pro: Better S/N ratio with good mixers with line in (about 90 dB with SD302), better metering, better mic pre-amps, good limiters, possibility to mix from many mics, gain riding possible during the shoot.
Con: costs more, more cables, needs usually a soundperson.

3) 24 bit recorder capable of 20 bit true resolution (something like SD7xx)
Pro: safer level setting with 24 dB extra headroom, better mic pre-amps, no cable to camera.
Con: needs either TC (not available on cheap cameras like XH-A1) or slate for every take, more work in post. Costs as much or more than the camera.

Quality of the sound depend not from a thing that only record a digital data. A laptop works here as good as another recorder. With a good 24bit soundcard you have an excellent sound recorder. But you need microphone preamplifier with phantom power for condenser mic.
Behringer BCA 2000 ist a cheap mixer with mic preamps an integrated 24bit soundcard - but there are some smaler units there.
I am using it as a mobile soundstudio - most for recordings voice overs. I have 2 such units by my "artists" directly at they home for recordings small projects an sending it per email to me.
But by filming i am recording directly to the camera - of course by maximal possible level.

Thanks Petri, that's was very enlightening. Would the 24bit soundcard recorder that Ivan recommended (see above) be equivalent to 20 bit too?

How much is an SD7xx? I couldn't find them on Google Shopping. Would it be better than the sound card?

The no cables to camera option is very attractive as they are very awkward and get in the way on dolly shots. They also make moving the camera between shots much more laborious. I have someone operating the sound equipment on set so a recorder operator is not a problem.

Thanks Petri, that's was very enlightening. Would the 24bit soundcard recorder that Ivan recommended (see above) be equivalent to 20 bit too?

How much is an SD7xx? I couldn't find them on Google Shopping. Would it be better than the sound card?



Only the better and best recorders achieve 20 bit resolution, I doubt any soundcard recorder does. Maybe 17-18 bit resolution, just guessing. By the way, even the VERY BEST rack mounted AD converters like Lavry and Weiss costing around 10k$ get 127 dB = 21 bit resolutions. So thinking about getting real 24 bits form a $300 pocket thing is absurd.

SD7xx refers to Sound Devices 700 series recorders (702, 722, 744 and 788 in different variations). They cost from $1875 to $5995 (B&H prices). Generally considered the best field recorders there are, in top 3 anyways. I have SD722 recorder and SD302 mixer, great tools.

Sound Devices, LLC | Professional, Portable Audio Products (http://www.sounddevices.com/)

Most if not all sub $2000 recorders have so much noise that 24 bits is not any better than 16 bits. The recorder does put out a 24 bit file, but tha extra 8 bits are just noise.
Definitelly NO. 8 bit "extra" are not 8 LED of levels even not higher levels ranges - but abot 366 times higher resolution.
Most of equipment noise comes from their analog devices - specially mic preamps. This will be of course quantisated too and saved in digital form and this makes smaller dynamic range - not the ADC, not the 24 bit recorder.
There is much much less digital - quantisation noise in 24bit as in 16bit (shown on my first figure) and even 18bits give you much more quality and important here - much more headroom (enabling lover levels recording) to avoid oversteering as a 16 bit system. Even 18 bits are 4times more resolution.
24 bit are not "8 extra" bits or extra levels. Its a diference between 65 536 levels and 24 Million Levels.
You don`t wanna really say that in 24bit they are 23,93 millions of levels only noise?
Yes - its right - most of microphone preams are definitelly not in possible dynamic ranges of 24 bit recorders. ( by recording live you will not a find dynamic ranges about 60dB) Here - by recording to lover levels to avoid oversteering is ist everytime better to record in 24bit and avoid adding quantisating noise. Remember: recording to -6dB ist recording with HALF resolution. Its still better to record with 12 millions levels than with 33 000 levels. Recomended Behringermixer ist of course the cheapest thing and it has in this pricelist excellent mic preamps. Such XHA1 is an excellent camera but has no chance i comparison with a HDW 750 for 60 000 Euro.

"Only the better and best recorders achieve 20 bit resolution"
No. Only the better and best recorders achieve maximal dynamic range theoretically allowed by 20 bit recording.

Here is an article to shown a difference by size (amplitude) of the signal relative to full scale (full amplitude) by comparison between 8 and 12 bit. Difference between 256 values (8 bits) and 4096 values (12bits). 16timer more resolution. This is exactly the some principe as a difference between 16 and 24 bits. But the dynamic range is a difference between max. possible amplitude and noise level. If there is a high noise level from the mic preamp - even horrible to -12dB - you will have only 12dB of dynamic range but this quantisated to 6 million levels (24bit) or only 16 000 levels (16 bit)
Resolution Compromise 8 to 12-bit (http://academic.hws.edu/geo/logger/Conversion/ResolutionExample.html)
I will try to say - 24 bit vs 16 bit is like HDTV vs SD in audio. Or better 4K vs SD. If you wanna zoom in twice the picture (volume adjustment from -6dB to 0dB) and convert to SD (to 16 bit) - its always better to shoot in High Definition. Still better to shoot with XHA1 in HDV - even if not soo good as with the RED 4k.

I see what you're getting at. Thanks Ivan.

The laptop and 24 bit soundcard/mixer sound like the best option to me at the moment. It seems it would record much better quality audio and there would be no need for cables connected to the camera. As long as I use a clapper board to synchronize the sound with the video in editing. The other possibilities for improving audio quality are too expensive for me.

What's ADC by the way? Analogue to digital converter?

There is a basic misunderstanding about digital audio floating around here, Ivan.

The fact is, that this "umpteen million more levels of resolution" all reside at the bottom of the dynamic range scale. That is why with more bits you get more dynamic range; i.e. smaller details and quieter sounds can be resolved. Mathematically it is measured in dynamic range and expressed in dB, ONLY. Calling it "detail" or "resolution" is misleading.

If we have two systems, 16 bit and 24 bit, which both are fed with 90 dB S/N electronics, we get a digital file with 15 bit equivalent dynamic range. One file has 1 bits worth of noise, the other 9 bits worth. The useable audio signal is identical on both. This is what I meant by "just having 8 bits of noise".

Now, this 24 bit file mentioned above has no extra "detail" or "resolution" in the top 90 dB clean range. All that imagined extra resolution and detail is in that 8 bits of extra noise compared to 16 bit file. For this reason the analog electronics are the limiting factor and thinking that using a cheap 24 bit recorder is giving a huge improvement in quality is just fallacy. If using more bits would do what misinformed people here are proposing, we would not have stopped at 24 bits, but would be using 30, 36, 42 bit systems. But we are not, because engineers designing the AD converters and systems know better.

This is getting too far from the original topic, so I'll stop here.

I thought I kind of understood. But now I'm completely confused.

Doesn't the signal to noise ratio depend upon the conditions you are recording in - not whether you use a 16 bit or 24 bit recorder? For example, if you record in a room with air conditioning you would have a lot of unwanted background noise effectively lowering the dialogue's s/n ratio. Will a 24 bit recorder give a massive decrease in s/n ratio compared to a 16 bit one? Noise would also originate from poor electronics I imagine.

Why would the extra 8 bits all be filled with noise? Wouldn't that make 24 bit recording completely pointless?

Surely a 24 bit recorder will allow the signal from the preamps to be captured more accurately than a 16 bit recorder even if it's not delivered to the recorder in 24 bit format?

No reason for confusion.

The recording systems makes no judgements on what is wanted signal and what is noise. It attempts to record everything as well as it can. How could it tell what is dialog and which is unwanted machinery noise, for example?

Noise in this context is not the noises we hear on set which we try to avoid recording (that is another matter more to do with miking practises, choosing the location etc), but noise caused by the less than perfect recording system: mics, mixer, mic preamplifiers and AD converter. It is all electronically generated and we hear it only on the recording or when monitoring it.

Sampling bit depth, either 16 or 24 bits, dictates the accuracy of the samples. Simply put, how small are the smallest voltage variations in the incoming signal which can be recorded. AD converter system measures voltages, for that reason one additional bit can describe twice as big voltage differentials and thus one bit more gives 6.03 dB more dynamic range potential to the system.

There is no other measurement tool for this accuracy, only the difference between smallest and largest possible voltage (waveform) and the relative logarithmic unit dB is used. If you want to use "normal" number ratios, you just raise 10 to dB/10 power (10^(dB/10)).

Dymnamic range does not mean only the difference between the quietest sound and loudest in a given recording, but also the difference between the smallest detail and the general level of the signal. Remember that the sound wave is very complex single waveform which contains all the levels and frequences in one single wave.

Now, let's imagine a perfect clean mic signal with 144 dB dynamic range going to a cheap 24 bit recorder. Cheap electronics add so much noise, that the finest 48 dB/8 bits of detail is buriend under it. We have 96 dB of clean signal and if we listen loud enough (this is important, we never do...), we hear just noise under this good signal. Feeding this same signal to a 16 bit recorder we get the same 16 bits worth of good signal, and if we turn up the volume, we hear just noise just like before. Both recordings are of same quality.

The misunderstanding about this "resolution" and dynamic range thing is that people forget that this dynamic range is the relative measurement of the smallest detail level piggybacking the large amplitude waveforms. If the dynamic range is large (like in good 24 bit systems), then there is more "resolution". If the noise level is high, then in a 24 bit signal these minuscule details piggybacking the waveform is not real signal, but random noise. It can not be called "detail" or "resolution".

Like I said before, if just using more bits for sampling would really improve the signal quality regardless the noise floor provided by the less than perfect analog circuits, we would certanly be using 48 bit systems by now. But we are not. That is because there is no point in using more bits than what the other parts of the chain can feed. With the best analog electronics and microphones the limit is around 130 dB which translates to 22 bit sample depth (For this reason 24 bit AD converters are plenty good enough and nobody even tries to use more).

Back to cheap recorders: with high noise electronics these recorder's 24 bit AD converters are not fed with a signal which has more than 96 dB or so dynamic range. So there is NOTHING those 8 extra bits compared to 16 bit recorders can do exept record this random noise faithfully. For that reason 24 bit files have exactly the same data content in the top 16 bits as a 16 bit file of the same signa, and ONLY noise in the last 8 least significant bits. That makes using 24 bit recording pointless, UNLESS the electronics & mics actually are capable of more than 96 dB dynamic range. With most cheap recorders they are not.

And finally, to put this all into perspective: 16 bit recording is wastly better than any analog recorders are capable of. Tens of thousands of high quality movies have been recorded in not-so-distant past using $15000 analog Nagra recorders, with ONLY about 65 dB dynamic range (11 bits...). Now, amateurs are panicing if they are not getting true 24 bit resolutions = 144 dB dynamic range from their $300 pocket recorders! Come on, in XH-A1 we have qualitywise a much better audio recorder than those glorified Nagras. That surely can not be the reason why we can not make great movies with great audio?

1.
If we have two BW pictures - one in 8 bit resolution and the some with 24 bit resolution. Both have he some dark poinst at zero black level, brithness and full white points. Both pictures have the some dynamic range. But the 24bit picture has 24 million levels between black and white - 24millions of grey levels. 8 bit picture has only 256 levels. This is the some as a difference between recorded audio signal.

2.
To be exactly - dynamic range is difference between max and min possible writable level.
By 24 bit resolution - we can write 0000.....001 and this - lovest writable level will be 1/24million of possible max level. By 8 bit resolution we have 00000001 and this is 1/256 of possible max level. The lovest level about zero is 366 times bigger than by 24 bit! This is the difference. Lower first step = greater dynamic range. Finer details just about zero = greater dynamic range. If we have not a really deep black in our pictures - because dark areas are noisy - we have pictures with lover dynamic range - but the 24bit picture has still finer grey graduations.
The some in audio. We record to max level - to 0dB. Every 6dB to minus is a half of the level. Logarithmic. -24dB ist a 1/16 of max. possible level. -30dB 1/32 of maximal level.
What if we have a ground noise level on -30dB? We have very low dynamic range - only 30dB. But how much possible levels - how fine steps are about noise level? We can`t use 1/32 of all levels - because this area is only noise. 24millions/32= 750 000. This is what we can`t use. Usable area has still 23,25 million levels.
Horrible dynamic range - but still much greater quality due to excellent resolution above the noise level.
Its mistake to say - we record with only 30dB dynamic range - so we have only ~8bit resolution and 16 bits are only noise. The difference in dynamic range makes the "quality" in lovest audio levels - but better resolution works in whole area - even to loudest 0dB.
Audio resolution and audio levels are linear - but dynamic range logarythmic and we have to different this.
3. Back to the point here.
We record audio - but not to 0dB to avoid oversteering by unexpected louder sounds.
We record to -6dB - to half of a full possible level. We record a real life sounds - probably nothing will have a dynamic about 60-70 dB. Yes - for this dynamic range in full levels will be 16 bit still more than enough. But by recording to -6dB we use only a half of 16 bit resolution!
In postproduction we have to do sound levels twice as louder - to have in final levels to 0dB. So - we make all sound louder - even noise = it will be no better dynamic range. But even quantisation steps will be twice as bigger! This is the some as scaling to different range here:Resolution Compromise 8 to 12-bit (http://academic.hws.edu/geo/logger/Conversion/ResolutionExample.html)
We have here a final sound - with twice as big quantisation steps as by recordings directly to 0dB! And this is the problem.
If we record in 24 bit to -6dB an makes normalising to 0dB - every quantisation step is still 366times finer. After downconversion to 16bit - the is much better quality.
Even postproduction makes sense to use 24bit recording. This is still not enough. Probably ever better music software uses 32bit resolution and temporary files for every processing -even on 16bit files.

16 bit recording is wastly better than any analog recorders are capable of.
Absolutelly NO. Dynamic range is not the only one aspect of quality.

Now, amateurs are panicing if they are not getting true 24 bit resolutions = 144 dB dynamic range from their $300 pocket recorders!
There is definitelly no problem today for any recorder to have true 24 bit resolution. The problem is on analogue devices side on recording equipments. Its no a technical problem to produce smalest 24bit ADC with an precise 1bit technology - but its a problem to deliver them analogue signals with 144dB dynamic range. Its a problem to find any signals wit 144dB dynamic range.
If minimal noticeable for peoples ear sounds are by 0dB - a jet airplane products still only 120dB about this! A normally conversation is at 60dB. Remember - this is a logarithmic range.
120dB is not twice as loud as 60dB. 66dB is it. 72dB is 4 times louder as 60dB.
So 144dB is 16 times louder as a jet airplane with 120dB!
So - why in the hell would anybody produce a recorder with 24 bit if there were nothing more as a dynamic range? To record simultaneously lovest sounds and 16 starting Jets?
If we had ability (mics preamps and recorders) to record simply even half of this dynamic range - the audio level regulators are useless.

1.
If we have two BW pictures - one in 8 bit resolution and the some with 24 bit resolution. Both have he some dark poinst at zero black level, brithness and full white points. Both pictures have the some dynamic range. But the 24bit picture has 24 million levels between black and white - 24millions of grey levels. 8 bit picture has only 256 levels. This is the some as a difference between recorded audio signal.


This analogy is invalid. In audio having more sample depth means the quetest parts can be more quiet. In photography this would mean that blacks would be blacker. Zero blackness is called "black body" in physics, theoretical term impossible to achieve in reality. If your photograph would be analogous with audio, black in the the 24 bit photo would have a reflectance of 0.00000596% and in 8 bit photo 0.39%. Quite a difference. In photography first the dynamic range is set governed by the sensor quality (typically 7 to 12 bit equvalency = 42 to 72 dB dynamic range), then this range is quantified with certain accuracy, typically 8 bits, sometimes 14 or 16. In audio one bit is always 6 dB.

Case 2 is a complete mess. Hopeless. You have the math upside down. Fine gradiations in the signal are the bottom part of the dynamic range. If it is noise, it is noise.

So - why in the hell would anybody produce a recorder with 24 bit if there were nothing more as a dynamic range?

There is no other measure or unit of this quality than dynamic range. It all boils down to dynamic range: ratio between the total maximum amplitude and the finest details in that waveform.

24 bit recorders are made for 2 reasons: 1) because we can, and: 2) using 24 bit sample depth with good front end gives more latitude and safety in recording when aiming for maximum quality end result, even if the said result is usually 16 bits (which in real life is much better than the reproduction systems and listening rooms).

There is no other measure or unit of this quality than dynamic range. It all boils down to dynamic range: ratio between the total maximum amplitude and the finest details in that waveform.

Thanks Petri.
Generally we have finest details in 24 bit vaweform and lover quantisation noise. So it still make sense to use 18, 20 or 24 bit if we record to -6dB and normalize in postproduction. Because recording to -6dB we use only a half of the maximum amplitude and we add less quantisation noise to the noise of analog side.