ACELP | ADPCM | AMBE | AMR | AMR-NB | CELP | Codebook | DTMF | G.723 | G.726 | G.729 | GSM | Interpolation | LPC | LSF | LSP | MELP | PCM | Perceptual | Pitch | PSOL | QCELP | Quantization | SMV | VAD | Vocoder

Thanks Dejun. By the way, so if I pack the actual encoded bits on a per fra=
me basis and save it as a .amr file, then would any player that plays 3GPP =
format audio files be able to play them? I plan to try this out anyway, but=
 just wanted to know if the file would be recognized as a 3GPP content or i=
s there some other processing that is done on this before it can be recogni=
zed and played in any of the 3G mobile phones?

Cheers,
Ashwin

----- Original Message ----
From: =E5=BC =E5=BE=B7=E5=86=9B <z...@huawei.com>
To: Ashwin Chandrasekaran <a...@yahoo.com>; Rama Krishna K <kosuriram=
a...@gmail.com>
Cc: s...@yahoogroups.com
Sent: Tuesday, August 5, 2008 6:50:20 PM
Subject: =E7=AD=94=E5=A4=8D: [speechcoding] AMR-NB codec
=20
Hi,Ashwin,
=20
    The reason is that,for each bit of the output of AMR-NB encoder is=20
represent by a WORD,for example, "0X81" represents "0",and "0X7F"
represent=
s "1"=20
in the bitstream.For example,if u use MR122 mode to encode a speech file. y=
ou=20
will get 244 bits per frame,but in each frame,each bit will be changed into=
=20
"0x81" or "0X7F".So the output of encoder will be bigger than the
input.may=
be=20
you can find more details in 3GPP website or ITU-T website.
=20
Hope this will=20
help u.
=20
Regards,
Dejun
________________________________
 =E5=8F=91=E4=BB=B6=E4=BA=BA: s...@yahoogroups.com=20
[mailto:s...@yahoogroups.com] =E4=BB=A3=E8=A1=A8 Ashwin=20
Chandrasekaran
=E5=8F=91=E9=80=81=E6=97=B6=E9=97=B4: 2008=E5=B9=B48=E6=9C=886=E6=97=A5 04:=
32
=E6=94=B6=E4=BB=B6=E4=BA=BA: Rama Krishna=20
K
=E6=8A=84=E9=80=81: s...@yahoogroups.com
=E4=B8=BB=E9=A2=98: Re: [speechcoding]=20
AMR-NB codec

Hi=20
Rama,

Sorry about the confusion. I actually meant the file at the output=20
of the AMR-NB encoder alone (not the decoded output) . Anyway, thanks for t=
aking=20
time to answer my questions.

Cheers,
Ashwin

-----=20
Original Message ----
From: Rama Krishna K=20
<kosurirama@gmail. com>
To: ashwin_c29=20
<ashwin_c29@yahoo. com>
Cc:=20
speechcoding@ yahoogroups. com
Sent: Monday, August 4, 2008 11:24:44=20
PM
Subject: Re: [speechcoding] AMR-NB codec :

Hi Ashwin,

Please=20
find answers below.

Regards,
Rama

On 03/08/2008, ashwin_c29=20
<ashwin_c29@yahoo. com>=20
wrote:
>
> Hi All,
>
> Had a small doubt regarding the=20
AMR codec.
> Why is the file size (file
> obtained at the output of=20
an AMR-NB codec) constant for all AMR rates
> even though there is a=20
different bit allocation for each 20 ms speech
> frame of the input file=20
corresponding to each of these rates.
[Rama]: AMR-NB codec contains both=20
Encoder and Decoder.
Encoder encodes each 20ms speech frame to corrresponding=20
bit rate
specified at the encoder.This is the place where compreesion=20
happens.
for example if you are encoding using 12.2kbps,same 20ms will=20
be
represented by 244 bits.
At the decoder,using these 244 bits we get 160=20
samples (20ms * 8Khz).

>(Besides the file size is also larger than=20
that of the input file).
[Rama]: So once it got decoded the file size should=20
be same as input file.
But perceptually both will be same.

> Am=20
still a novice as regards this codec and haven't been able to figure this=20
out.
> It would be nice if someone could throw some light on=20
this.
>
> Thanks,
>=20
Ashwin.

=20=20=20
=20=20=20=20=20=20

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