rg wrote:> "Jerry Avins" <jya@ieee.org> wrote in message > news:412a6a30$0$21745$61fed72c@news.rcn.com... > >>rg wrote: >> >> >>>Hi, >>> >>>Thank you very much for your reply. You clearly have a very good >>>understanding of the GSM codec. If you don't mind, I would like to ask > > you a > >>>follow up question. >>>As you make clear, the GSM audio codec is very inappropriate for music, > > but > >>>is there any way of analysing an audio/music file in order to evaluate > > how > >>>much distortion there would be if fed through the system. For example, > > is it > >>>possible to get a measurement of how well the codec is able to model a >>>particular sound source. >>> >>>Many Thanks for your help, >>> >>>RG >> >>That one is easy enough even for me. Pass your file through a model >>system and measure the distortion that results. If you want to see how >>badly a lens distorts, take a picture with it. >> >>Jerry >>-- >>Engineering is the art of making what you want from things you can get. >>����������������������������������������������������������������������� >> > > > Thanks for your reply. > > I have considered doing what you recommend. Essentially analysing the > correlation between the source file and the gsm version of the file. However > my concern is that since GSM is supposed to be a lossy codec, the two > versions will almost always be different. Would it be possible to identify > the distinction between information just being removed due to the coding > mechanism and actual distortions being introduced into it? I hope what I'm > trying to say here makes sense. > > Thanks, > > RGIt makes sense to me, but is seems like the technique for determining if a number is divisible by seven. It exists, but it's more of a chore to apply than it is do do the division. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Music through GSM codecs, use of psychoacoutic codecs
Started by ●August 22, 2004
Reply by ●August 23, 20042004-08-23
Reply by ●August 25, 20042004-08-25
Hi, Sometime back we were using a tool called OPTICOM (I think) for comparing the original music and the encoded music (for mp3 encoder). That takes care of so many things and mostly models the ear. Basically it checks the distortion is audible or not. Maybe that will be useful to compare how good the codecs behave. Anandh Jerry Avins <jya@ieee.org> wrote in message news:<412aa657$0$21760$61fed72c@news.rcn.com>...> rg wrote: > > > "Jerry Avins" <jya@ieee.org> wrote in message > > news:412a6a30$0$21745$61fed72c@news.rcn.com... > > > >>rg wrote: > >> > >> > >>>Hi, > >>> > >>>Thank you very much for your reply. You clearly have a very good > >>>understanding of the GSM codec. If you don't mind, I would like to ask > > > > you a > > > >>>follow up question. > >>>As you make clear, the GSM audio codec is very inappropriate for music, > > > > but > > > >>>is there any way of analysing an audio/music file in order to evaluate > > > > how > > > >>>much distortion there would be if fed through the system. For example, > > > > is it > > > >>>possible to get a measurement of how well the codec is able to model a > >>>particular sound source. > >>> > >>>Many Thanks for your help, > >>> > >>>RG > >> > >>That one is easy enough even for me. Pass your file through a model > >>system and measure the distortion that results. If you want to see how > >>badly a lens distorts, take a picture with it. > >> > >>Jerry > >>-- > >>Engineering is the art of making what you want from things you can get. > >>����������������������������������������������������������������������� > >> > > > > > > Thanks for your reply. > > > > I have considered doing what you recommend. Essentially analysing the > > correlation between the source file and the gsm version of the file. However > > my concern is that since GSM is supposed to be a lossy codec, the two > > versions will almost always be different. Would it be possible to identify > > the distinction between information just being removed due to the coding > > mechanism and actual distortions being introduced into it? I hope what I'm > > trying to say here makes sense. > > > > Thanks, > > > > RG > > It makes sense to me, but is seems like the technique for determining if > a number is divisible by seven. It exists, but it's more of a chore to > apply than it is do do the division. > > Jerry
Reply by ●August 25, 20042004-08-25
axlq@spamcop.net (axlq) wrote in message news:<cgbsev$bqu$2@blue.rahul.net>...> But those artifacts may not be audible on an "audio system" that > consists of an audio signal of narrow bandwidth and a tinny speaker > of narrow bandwidth. I imagine there's a lot of information one > could cut out without much loss to what one actually hears.The artifacts can get especially ugly when transcoding. Try this one for example: wave -> gsm -> wave -> mp3 ...you'll hear some truly bizarre chirping and gurgling sounds at times so it appears sticking with one codec would result in the best quality--with "best" being a relative quantity when such low bitrates are involved. =) GSM used to transmit speech does have its issues. For example, look at the http://atnac2003.atcrc.com/POSTERS/Chong.pdf file. Considering that various Chinese phonemes may get mangled in some cases (!), music remaining aesthetically pleasing probably doesn't stand much of a chance. -t
