256 kbps Vs 320 kbps

[nandac]

is there any discernible difference between the above two bit rates (in itunes) when it comes to playback clarity?

some views (on the net) seem to indicate that while not much difference can be heard using a headphone, but if you play the files though amp/speakers, difference in quality become more apparent.

any views on this?

 

[arj]

nandac, the resolution you hear would depend on the capability of the gear to resolve the same, irrespective of it being a headphone or a amp/speaker.

there are folks who are able to differentiate between different pressings of CDs (US Vs Eu Vs japan) so 256 vs 320 may just be easier to determine.. and so is 320 vs lossless.

 

[baijuxavior]

there are folks who are able to differentiate between different pressings of CDs (US Vs Eu Vs japan)

Are you saying different pressings of CDs have different bits in them? Unless they are of different audio recording sessions, a cd will have the same bits irrespective of manufacturing technology. So how can one differentiate between the two? It may be true in case of analog recordings like cassette tape, lp records etc, but not with digital cds.

 

[arj]

Are you saying different pressings of CDs have different bits in them? Unless they are of different audio recording sessions, a cd will have the same bits irrespective of manufacturing technology. So how can one differentiate between the two? It may be true in case of analog recordings like cassette tape, lp records etc, but not with digital cds.

baijuxavior, a cd is not encoded in bits. it is encoded in words as pe the Redbook Standard . reading a cd is based on an algorithm (Reed Solomon) which "supposes" the result into a stream of bits with a clock. so if the cd isnot pressed well the result is different as the transport does not do multi reads as in a computer CDROM.

try any indian pressing with the US pressing...the sound will be pretty different in a medium resolving system as well.

This is a slightly long read on a different context but gets to the point rather nicely

this is the reason as to why Japanese pressings are regarded so well. further in a cd there are 2 templates a Glass "Father" which is created from the Master and 4 metal "Mothers" which are created from the father.apparently there is a difference in pressings between the 1st and 4th mother which can (apparently) be differentiated although i have never got a chance to compare.

 

[baijuxavior]

thanks for the explanation. My ignorance.

 

[deba]

If you play in high resolution system than difference is audible but in a standard audio system or portable audio device difference between 256 and 320 is very difficult to detect........

 

[ark]

baijuxavior, a cd is not encoded in bits. .

Hi, Are you sure about this ? I thought what is written to the CD is a series of 1s and 0s and what is read from the CD is also a series of 1s and 0s.

 

[gobble]

It is bits all right, but the data in redbook format is not in packet format that can be buffered like mp3 or flac data file. So misreading a bit means no time to recover accurately and hence SQ will suffer.

HTH

 

[arj]

Hi, Are you sure about this ? I thought what is written to the CD is a series of 1s and 0s and what is read from the CD is also a series of 1s and 0s.

well that is what i could find out as i was trying to understand why my two CDR copies sounded different
If you have the patience and the interest please do go through this..i found it rather well written

More than Meets the Ear
From the explanation given so far, it would seem that recording and playing back a CD is a simple matter of "ones and zeros in, ones and zeros out." If it were only that easy!

The fact is that over two-thirds of the ones and zeros on a CD are not part of the original raw data! This is because the incoming bits are subject to a whole series of encoding processes before they can be stored on CD in a robustly readable form. The encoding method used on audio CDs is called CIRC, which stands for Cross-Interleaved Reed-Solomon Code. CIRC adds a whole bunch of extra (but vitally important) information to the final recorded CD. This information contains bits which provide relative and absolute timing information, track and index placement, emphasis and copy-protection bits, synchronization data, error prevention and correction data, and merge bits to keep it all straight. Not only is a ton of extra information added, but it all gets scrambled and spread around before it's laid into the data track -- which makes error recovery a lot more reliable.

 

[ark]

well that is what i could find out as i was trying to understand why my two CDR copies sounded different
If you have the patience and the interest please do go through this..i found it rather well written

Thanks arj. I went though the article. Gives good info, but I was also looking for some details on how the time synch is done, which is not covered.

It is bits all right, but the data in redbook format is not in packet format that can be buffered like mp3 or flac data file. So misreading a bit means no time to recover accurately and hence SQ will suffer.

HTH

Gobble, thanks , I got that. Now I see that when I play an audio CD is my laptop, it reads the cd continuously. But if its an mp3 file , the reads happen intermittently. So it looks like quite a bit of buffering happens if the source is mp3 or similar.
Now I am wondering how the timing information is handled in both cases. Also , with the powerful processing that we get these days, real time correction should be possible on the data read from audio CD ? what is preventing the CD player from doing a read ahead ?

 

[prankey]

Buffering happens on MOST of the CD players to avoid interruptions due to shocks and read errors and Red book spec is not related to it. Also, in modern CD players, there are built in error correction ("C2") mechanisms built in which first detects error location and then performs multiple read cycle to try and recover errors (usually they are able to recover successfully).

Buffering is not recommended for Audio CDs in a CD drive and usually current CD drives turns it off so software error correction mechanisms (like in EAC) can work reliably (otherwise during software retry cycles, the CD player will simply pass the buffered data and hence would not contribute to error correction actual read cycles).

 

[no1lives4ever]

The best way to play audio cds is to rip the cds on a computer to a lossless format like wav or flac and then play using a computer/media player through a good quality AVR/DAC.

CD ripping software like EAC do not have any limits on how long they can take to rip a given CD, so they can perform multiple read retries on bad parts of a CD to ensure that you get the best possible rip of the CD.

This process is not as simple as popping a cd into a CD player and hitting play. You need to rip your CDs first. Then you need to play the ripped music using either a media player or a computer. A big advantage of this method is that you create a digital backup of your CD. This also prevents your audio CDs from getting scratches when played on a player.

-- no1lives4ever

 

[rohit3192]

256 vs.320 best thing is do ABX test and I bet with same player and same set of speakers/headphones you won't observe any difference.
Even I will go the extent that do ABX with 128 vs.320 and see if it is worth the extra MBs the 320 kbps files require.
I have 256 kbps AAC files and 3 times the data of same songs in FLAC and I can't differ.
What is a blind ABX test ? - Hydrogenaudio Forums

 

[prankey]

Yes, best is to encode using VBR with different quality levels and do an ABX. You might feel happy with even a 128kbps encoded file... Largely depends on the content type so we can not generalize if you would always get better audio in 320kbps encodes.

 

[arj]

256 vs.320 best thing is do ABX test and I bet with same player and same set of speakers/headphones you won't observe any difference.
Even I will go the extent that do ABX with 128 vs.320 and see if it is worth the extra MBs the 320 kbps files require.
I have 256 kbps AAC files and 3 times the data of same songs in FLAC and I can't differ.
What is a blind ABX test ? - Hydrogenaudio Forums

without getting into a discussion on the technicalities, the philosophy of Mp3 is to remove information to conserve size. in these days where cost/GB is miniscule and only getting lower, why wold you want to lose any information which is irrecoverable ?

as you go along your music journey and you only get better equipment which can illustrate this difference, you will only regret this loss all for a few paise !

Somehow irrecoverable loss of information with even a possibility of it being discerning is the option i personally would take in favor of retaining something which has only a possibility of being redundant.

A very good example is RPG saregama. many years back they digitized their music..all their new CDs with hindi songs are pathetic..and sound is screetchy. and anyone who has not heard these in the past would just not appreciate the music.

 

[Jith77]

256 vs.320 best thing is do ABX test and I bet with same player and same set of speakers/headphones you won't observe any difference.
Even I will go the extent that do ABX with 128 vs.320 and see if it is worth the extra MBs the 320 kbps files require.
I have 256 kbps AAC files and 3 times the data of same songs in FLAC and I can't differ.
What is a blind ABX test ? - Hydrogenaudio Forums

completely agree.....i had done the test about 3-4 years ago(headphones)...the purpose was to figure out at what bit rate i should rip audio CDs (from a library)...

I had found that 256 did the job just fine. Since then my audio equipment has changed but i havent changed my minimum requirement of 256 as i didnt have the itch to figure it out all again.

If one requires an answer to this question and a satisfactory one, the only way would be to take the test oneself.