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Rockbox mail archiveSubject: RE: Question about CD-Quality and MP3RE: Question about CD-Quality and MP3
From: rob powell <rob_at_rinty.plus.com>
Date: Wed, 1 Feb 2006 10:50:48 -0000 Hi, 2 answers I'm afraid. First, because MP3 is by definition a lossie format, there will definitely be losses when converting a CD to an MP3 file. Whether you can hear it depends on your ears and your equipment: try it and see. Re the bit-rate and sample frequency you suggest, I'd move the sample frequency up to 48KHZ. Rob -----Original Message----- From: rockbox-bounces_at_cool.haxx.se [mailto:rockbox-bounces_at_cool.haxx.se]On Behalf Of Selamet Aydogdu Sent: 01 February 2006 10:32 To: 'Rockbox' Subject: AW: Question about CD-Quality and MP3 Hi Rob Thank your verry much for your detail infos. I have yet i hope a last question: On witch samplerating and hz you can't hear definitly the different between a Sound on a CD and sound on an MP3-File? Somebody thinks, that a compression with 224 kbps, 44100hz, VCR-Level 4 it's sufficient to reach the CD-Quality. Some tests and knowhow can be verry interesting. Greetings Selamet > -----Ursprüngliche Nachricht----- > Von: rockbox-bounces_at_cool.haxx.se > [mailto:rockbox-bounces_at_cool.haxx.se] Im Auftrag von rob powell > Gesendet: Mittwoch, 1. Februar 2006 11:11 > An: Rockbox > Betreff: RE: Question about CD-Quality and MP3 > > > Hi, > > Not sure I understand the question entirely, but here's some help. > Hopefully it'll be of use to others too. > > These comments are obviously not all-encompassing, but they > do to gain an > understanding. There are 2 elements to the quality of a > digital audio file, > whether it be MP3, Ogg, or whatever. Sample frequency and bit rate. > > First, professionally produced audio CD's are always sampled at 48KHZ, > whereas most MP3's and minidisks tend to be sampled at 44KHZ. > Second is the > bit-rate, not so critical as the sampling rate, but still > important. Most > MP3's are recorded at 128KBPS, (kilobits per second), though > of course you > can record at whatever value you want, provided your MP3 > player will support > it). I for example record books at 48KBPS, 22K sampling > rate, and mono. > > It's generally agreed however that to obtain CD quality, you > need to be > recording MP3's and any other audio format for that matter at > 192KBPS. For > reasons that I'll go on to explain, it's not actual CD > quality, but it's > recognised to be audibly very close, and barely noticeable. > > There are basically 2 types of digital audio formats, lossie > and lossless. > Lossless create larger files, lossie ones smaller. .MP3 .ogg > and .wma are > examples of lossie formats, .wav is a lossless format. The > issue is not > whether you loose anything by converting to MP3, but whether > you'll notice > what you loose on the equipment you're using for playback. > 44KHZ and 128KBPS > are generally recognised to provide an adequate level of playback for > portable digital audio devices, and indeed I find that > generally to be true: > however when I connect the Archos or Iriver to my hifi > system, I can hear > the difference quite easily between the CD and the music on my player. > Basically it's horses for courses. > > Inevitably however there's a trade-off between file size and > quality. You > don't actually need an audio book (speech) to be the same > quality as your > favourite album: so you can get away with lower bit-rates and sample > frequencies, which mean smaller files, and less space on your > MP3 player. I > change the bit-rate and sample rate quite a bit, depending on what I'm > recording. Old football matches recorded from AM don't need > to be recorded > at a high bit rate and sample frequency, as the bandwidth of > AM limits the > quality of the original. Well-recorded stereo radio dramas > however benefit > from higher recording quality. > > The generally accepted rule is, that the MP3 standard is good for many > reasons, not least because all digital music players will > play it. However > Ogg Vorbis WMA and others have advantages. Ogg Vorbis files > take up less > space for the same sample and bit-rate size. It's also a more modern > encoding standard, and therefore the quality of a file will > be higher if an > MP3 file and an Ogg Vorbis file of the same size are > compared. However a > .ogg file and an MP3 file recorded at the same bit-rate and > the same sample > rate will be of very similar quality. That's as I understand > it, if I've > got it wrong, I'm happy to take corrections: as I'm a bit hazy there. > > Gary, you might know more. > > I think that all the units that'll take rockbox are > capable of reading > files from 32 to 320KBPS, and with sample rates of 22 to 48KHZ. > > In short, the lower the bit rate and sample frequency, the > smaller the file, > but the poorer the playback quality. > > HTH, > > Rob > > -----Original Message----- > From: rockbox-bounces_at_cool.haxx.se > [mailto:rockbox-bounces_at_cool.haxx.se]On > Behalf Of Selamet Aydogdu > Sent: 01 February 2006 09:32 > To: rockbox_at_cool.haxx.se > Subject: Question about CD-Quality and MP3 > > > Hello, > > I search some sources that describe the different about MP3 > and CD-Quality. > If it's possible that you can hear the same sound in MP3, > that exists too in > CD-Quality? Whats about OGG? > > Greetings > Selamet > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.375 / Virus Database: 267.14.25/247 - Release > Date: 31/01/2006 > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.375 / Virus Database: 267.14.25/247 - Release > Date: 31/01/2006 > > -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.14.25/247 - Release Date: 31/01/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.14.25/247 - Release Date: 31/01/2006Received on 2006-02-01 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |