DVD sounds far better than audio CD - why?

[smillion]

I have started playing music DVDs on the comand and the sound quality is outstanding compared to regular CDs; radio or FM linked i-pod.

Now I can perhaps understand the reason why FM linked i-pod struggles to compete buy why is it soooooo much better to listen to a dvd rather than a CD?

All recording are original and no copies just in case that were relevant.

Thanks

Marc

 

[grober]

HowStuffWorks "Is the sound on vinyl records better than on CDs or DVDs?"

 

[Diesel Benz]

HowStuffWorks "Is the sound on vinyl records better than on CDs or DVDs?"

That description of CD audio isn't quite accurate. I hope someone is willing to spend time describing the theory but a 44kHz sampling rate theoretically allows lossless representation of 22 kHz bandwidth, give a bit for practical low pass filter implementation and you can cover a bandwidth from zero to 20 kHz. The 16 bit word length gives some 96 dB dynamic range. This combined exceeds the "capability of the car audio environment", taking into account the noise floor from the engine and tyres etc. Equally the speakers are not able to handle the bandwidth, perhaps the dynamic range yes but this does not help if you don't want to listen to sounds levels exceeding 120 dB.

The DVD sound probably has some surround sound effects or similar, or do you actually have Logic 7 audio with multichannel capability which DVD audio can make use of? The difference can be real but it is still not "physical" and not explained by the higher sampling rate etc.

Another source for reference added:
http://en.wikipedia.org/wiki/Signal-to-noise_ratio

 

[smillion]

 

[smillion]

In fairness I have looked at Grober's link and there appear to be some explanation.

Whereas, DieselBenz's reply, whilst welcome, may as well be written in Russian.

Thank you for taking the time to reply however.

 

[grober]

That description of CD audio isn't quite accurate. I hope someone is willing to spend time describing the theory but a 44kHz sampling rate theoretically allows lossless representation of 22 kHz bandwidth, give a bit for practical low pass filter implementation and you can cover a bandwidth from zero to 20 kHz. The 16 bit word length gives some 96 dB dynamic range. This combined exceeds the "capability of the car audio environment", taking into account the noise floor from the engine and tyres etc. Equally the speakers are not able to handle the bandwidth, perhaps the dynamic range yes but this does not help if you don't want to listen to sounds levels exceeding 120 dB.

Perhaps if you substitute "sound frequency range" for bandwidth it makes more sense?
Where sound quality suffers with slow sampling recording rates is with "clipping" where the dynamic range of the original analogue signal is flattened off due to rapid changes in peak signal levels being missed- think of someone chopping off the top of those nice sine waves so they are plateau like instead of smooth curves.That's the theory anyway-whether as Dieselbenz says it makes much difference in a car environment-who knows but smillion seemed to notice a difference?

 

[IanW]

It's possible that the music on the DVD has received more processing - a little compression to bring up the quiet bits so they don't get lost in the ambient noise, bass boost during the drum solos to give that earth shaking feeling, a touch more mid-range during vocals to make them clearer etc. And a general boost to the treble to make it all sound brighter.
Ian.

 

[Diesel Benz]

Where sound quality suffers with slow sampling recording rates is with "clipping" where the dynamic range of the original analogue signal is flattened off due to rapid changes in peak signal levels being missed- think of someone chopping off the top of those nice sine waves so they are plateau like instead of smooth curves.That's the theory anyway-whether as Dieselbenz says it makes much difference in a car environment

The theory says that the digitized signal would not miss any rapid changes if the sampled analog signal did not have components above 20 kHz (if it had, the speakers in the car would not be able to reproduce those anyway, and your ears, even if younger than mine, would not hear those) and the signal would be absolutely smooth after the D/A-converter and the low pass filter that is part of the signal reconstruction.

The "stepwise" digital signal would consist of harmonics, theoretically to infinitely high frequencies. Since the useful signal is within the 20 kHz useful "sound frequency range" anyway, everything above 20 kHz would be filtered with the reconstruction low pass filter after the digital to analog converter, all the "steps" have disappeared and the signal looks exactly the same as the input did.

If you have a look at the second link, from post #3, this all should be clear.

The first link gives intentionally misleading info, it is essential to notice that a 44 kHz sampling rate would already be sufficient to capture every signal change, slow or rapid, as long as the signal does not consist of frequencies higher than the human ear can hear. A higher sampling rate would mainly make the D/A reconstruction filter implementation easier because of a larger difference from end of useful signal frequency range to first harmonic that must be filtered away.

Note that I've never claimed the OP could not notice a difference, what I'm claiming is that it cannot be coming from the CD-audio coding capabilities.

 

[portzy]

It's possible that the music on the DVD has received more processing - a little compression to bring up the quiet bits so they don't get lost in the ambient noise, bass boost during the drum solos to give that earth shaking feeling, a touch more mid-range during vocals to make them clearer etc. And a general boost to the treble to make it all sound brighter.
Ian.

I'm with you on this, your, explanation. Its just what I wanted to say but couldnt find the right words.

Portzy.

 

[verytalldave]

To stick my 2 bobs worth in here........
Its interesting to note the OP's original wording of the question....
"DVD sounds FAR BETTER than audio CD"...........
Not wishing to put words into the OP's mouth, perhaps it might be more accurate to use the word DIFFERENT instead of BETTER.
IanW is probably quite correct in his guess that the audio signal on a DVD has been tweaked far more than on an audio CD. The whole point of an audio CD is to give a fairly accurate representation of the singers performance (for example). And as such will not have been tweaked or meddled with too much. Although in today's world, to find any modern audio CD that hasn't been altered by a studio engineer to give the ORIGINAL studio recording a lift by using either compression or any number of methods to enhance the recording is almost impossible except on a few serious classical recordings.
DVD audio on the other hand gets modified and changed by a huge degree before it gets to the home market. If you have ever heard a raw recording before an engineer gets his hands on it, it can sound a little flat and dull.
Much of it is done to compensate for the relatively poor audio equipment in most peoples houses. To help generally poor bass and treble reproduction, these frequencies are boosted to give the impression that the sound you hear is nearer to the original than would otherwise be possible. If we all had genuine studio quality equipment in our homes with large long rooms, then this wouldn't need to be done.
Even auntie BBC gets in the act. As far as I am aware the only radio station in the UK that doesn't compress its signal before transmission is Radio 3. And even they sometimes do it a little bit.
All the other stations - especially the commercial "pop" stations like Capital, Heart and Absolute compress their signals SO much that if you could compare the original uncompressed sound with that what you eventually hear in either your car or home, you would be staggered.
Remember, when you hear a modern music track on the radio in the UK, what you are hearing has probably had up to three completely separate stages of compression performed on it.
First at the time of the original recording, second at the time of laying down the final mix before burning the CD master and lastly before transmission by the radio station. No surprise then that most singers cant ever quite capture the same sound at a live gig.
Which is why the adverts on the TV commercial breaks sound so loud compared to the perceived audio level on the program that they interrupt. Its not because they ARE louder in MEASURABLE level, the audio has received a HUGE amount of compression which makes it sound louder to our ears. If you were to measure the advertisement sound levels using a dB meter they would appear to be at roughly the same level as the program. Which is why the advertisers state that their adverts AREN'T louder. But to our ears they SOUND louder. And its all down to signal compression.
What compression does basically is to make the louder sections of the music softer and at the same time boost the quieter passages. So it tends to even out the the audio spectrum with regard to sound pressure levels. So you can then lift the WHOLE audio track up before it clips to a higher perceived level or volume. Its a clever - but annoying - technique that has been used for many years in recording and broadcasting. If you want to hear music that hasnt been compressed dig out an old LP from the 1960's and give it a spin. Thats almost about the only way you will get to hear it. Or go somewhere to hear a singer and orchestra that hasn't been amplified - opera for example.
Go to a normal live concert with speakers and amplification and what you hear will have been compressed before it reaches your ears.

A better, fuller understanding of this subject can be found here..............
http://en.wikipedia.org/wiki/Dynamic_range_compression

Specifically related to dynamic compression used in advertising...........
http://www.statemaster.com/encyclopedia/Amplitude-compression

Sorry for all the waffle..........

 

[smillion]

You might have a point verytalldave.

To best describe the difference (whether technically better quality or not) :--

At home we watch TV on the regular TV audio. When we watch a film we use a Panasonic Home Cinema system. The difference in audio is stark.

.....................and it is this degree of DIFFERENCE between the music DVD in the car (Pink Floyd playing live) and regular radio or CD in the car. A huge difference.

Just thought it odd that some of friends invest many 1000's £ in home audio gear tp play CDs when, in my view, the audio from a DVD some in a different league - certainly on my Comand.

I was hoping someone would say they should be the same and that I need to change the settings on my CD.

The older ones on the forum will remember the days when you could fit a Graphic Equaliser toyour radio with AMP and the difference was fantastic. Well, I get the same difference ebtween CD and DVD in my car.

Thanks for your input. You will have gathered I am not technically minded

 

[verytalldave]

You might have a point verytalldave.

To best describe the difference (whether technically better quality or not) :--

At home we watch TV on the regular TV audio. When we watch a film we use a Panasonic Home Cinema system. The difference in audio is stark.

.....................and it is this degree of DIFFERENCE between the music DVD in the car (Pink Floyd playing live) and regular radio or CD in the car. A huge difference.

Just thought it odd that some of friends invest many 1000's £ in home audio gear tp play CDs when, in my view, the audio from a DVD some in a different league - certainly on my Comand.

I was hoping someone would say they should be the same and that I need to change the settings on my CD.

The older ones on the forum will remember the days when you could fit a Graphic Equaliser toyour radio with AMP and the difference was fantastic. Well, I get the same difference ebtween CD and DVD in my car.

Thanks for your input. You will have gathered I am not technically minded

Ah yes.

The reason some people spend sometimes vast and inordinate sums of money on hi-fi is to try to satisfy many parameters.
Not least truly ACCURATE reproduction.
But this is a subject that is far too deep to explore here in detail and is a minefield of information and disinformation.
Suffice to say, its sometimes done to impress, sometimes done because they can afford to indulge themselves but usually done to try to achieve a sound in their homes which gets as close as practical and possible to the original live performance.
To audio buffs, the SOUND many people prefer is not true hi-fi.
Difficult to quantify and VERY difficult to achieve.

 

[st13phil]

As far as I am aware the only radio station in the UK that doesn't compress its signal before transmission is Radio 3. And even they sometimes do it a little bit.
All the other stations - especially the commercial "pop" stations like Capital, Heart and Absolute compress their signals SO much that if you could compare the original uncompressed sound with that what you eventually hear in either your car or home, you would be staggered.

I think it's now only some of BBC R3's live broadcasts that don't have any compression at all, but even when they do use compression it's done with a much lighter touch than any other radio station I can think of. On decent quality home audio systems I can quite easily hear the broadcaster's compressor working on most music, and most readily on anything with a significant bass line or kick drum. In the car I rarely hear any compression effects other than the obvious one of limited dynamic range.

I think the best way to illustrate the effects of audio compression are to sit someone who has never witnessed an orchestra (or big band) play live in row 10 of the auditorium and get them to listen to a live performance that has significant crescendos in it. It's quite likely they'll be utterly shocked and may even need to use the "facilities" as a result

Back to the OP's point: As has already been suggested, the most obvious difference you're hearing is as a result of different eq and compression being applied when the dics were mastered rather than any inherent difference in the disc or player technology. Getting a bit deeper into it, there actually are improvements in reproduction possible by using a higher sampling rate than is used for standard audo CD's, but the reasons are somewhat obscure and none would explain the magnitude of difference you have described.

 

[verytalldave]

I like that...........
"............may even need to use the facilities........."
LOL.

You are of course completely correct.
Most of those who only ever listen to music by either CD or radio will be somewhat taken aback from a live performance by someone like Santana or even the Moody Blues.
Our ears and brain have become accustomed and attuned to a narrow dynamic range over the years.
And if you do treat yourself try to pick an acoustically good venue like the RAH. It may cost more but it will be worth it.

 

[timskemp]

Compression (as in dynamic range) is every pop producer's friend, and overused by most commercial radio stations and compilation album producers.

Compression (as in lossy audio compression such as MP3, Dolby Digital, MP2 and AAC) is every audiophile's nightmare - especially when aiming for lower data rates.

CD audio needs abour 1500 kbists/second. DVD Video soudtracks allow up to about four times that data rate, so if used for 2 channel audio can store much higher detail, and 96khz sampling is supported, some say there's no real difference but there is a distinctly different character to the sound.

DVD audio allows even higher rates.

 

[smillion]

Music dvds it is then where posible ...............................

they really do sound fantastic.