Forums

I/O File Size In G729

Started by bine...@gmail.com July 11, 2006
Hi,
Now I am working with ITU-T's G729 recommendation.The size of the input I given to this coder was 586 KB(16 bit PCM mono)and I got the output as 600 KB. Is this output's size is right or not? I think that, as an encoder it's output size should be less than input size( That is why we are encoding). The output is right,then What is the reson? Please clear my doubts immediately.
Thanks in advance
Bineesh Jose
Bineesh-

> Now I am working with ITU-T's G729 recommendation.The size of the
> input I given to this coder was 586 KB(16 bit PCM mono)and I got the
> output as 600 KB. Is this output's size is right or not? I think that,
> as an encoder it's output size should be less than input size( That is
> why we are encoding). The output is right,then What is the reson?

Part of the reason (but seems not all) could be unused bits in each PCM value in the
output .wav file. Suggest to display the output .wav file in software like
Hypersignal or CoolEdit, and note the maximum value. If the max value is small, for
example 128, then each coefficient is only 7 bits and you have 9 bits unused per
sample.

-Jeff
And maybe you are using the ITU file format for the coder output which uses
a 16 bit word for each bit of encoder output?

Chuck

>From: Jeff Brower
>To: Bineesh Jose
>CC: s...
>Subject: Re: [speechcoding] I/O File Size In G729
>Date: Tue, 11 Jul 2006 16:03:09 -0500
>
>Bineesh-
>
> > Now I am working with ITU-T's G729 recommendation.The size of the
> > input I given to this coder was 586 KB(16 bit PCM mono)and I got the
> > output as 600 KB. Is this output's size is right or not? I think that,
> > as an encoder it's output size should be less than input size( That is
> > why we are encoding). The output is right,then What is the reson?
>
>Part of the reason (but seems not all) could be unused bits in each PCM
>value in the
>output .wav file. Suggest to display the output .wav file in software like
>Hypersignal or CoolEdit, and note the maximum value. If the max value is
>small, for
>example 128, then each coefficient is only 7 bits and you have 9 bits
>unused per
>sample.
>
>-Jeff
You encoder is at fail, well you shoud recive the encoded data i.e
the output file in your case to be 586/8 as the compression ratio for
the g729 is 8 times, well the Input for the G729 is 16 bit data which
is sampled at the 8Khz, my question is did you sampled it at 8khz ?

On Mon, 10 Jul 2006 b...@gmail.com wrote :
>Hi,
> Now I am working with ITU-T's G729 recommendation.The size of the input I given to this coder was 586 KB(16 bit PCM mono)and I got the output as 600 KB. Is this output's size is right or not? I think that, as an encoder it's output size should be less than input size( That is why we are encoding). The output is right,then What is the reson? Please clear my doubts immediately.
>Thanks in advance
>Bineesh Jose
>
yes you are write. If you see the file format for the out put of the encoder, it is stored in word format i.e for example 2 is represented as 0x0002. Due to this the size of the output file is more than what is expected.

Regards
Sridhar. A

CHARLES HUTTON wrote:
And maybe you are using the ITU file format for the coder output which uses
a 16 bit word for each bit of encoder output?

Chuck

>From: Jeff Brower
>To: Bineesh Jose
>CC: s...
>Subject: Re: [speechcoding] I/O File Size In G729
>Date: Tue, 11 Jul 2006 16:03:09 -0500
>
>Bineesh-
>
> > Now I am working with ITU-T's G729 recommendation.The size of the
> > input I given to this coder was 586 KB(16 bit PCM mono)and I got the
> > output as 600 KB. Is this output's size is right or not? I think that,
> > as an encoder it's output size should be less than input size( That is
> > why we are encoding). The output is right,then What is the reson?
>
>Part of the reason (but seems not all) could be unused bits in each PCM
>value in the
>output .wav file. Suggest to display the output .wav file in software like
>Hypersignal or CoolEdit, and note the maximum value. If the max value is
>small, for
>example 128, then each coefficient is only 7 bits and you have 9 bits
>unused per
>sample.
>
>-Jeff