Re: [Lame-dev] Fwd: MP3 encoding question

[Alexander L. <Alexander@Leidinger.net>]

Hi,

such a question is better asked on lam...@li... (CCed). Sorry  
for the TOFU, but this way it's more easy to se that I sort of forward  
this question to lame-dev@.

Bye,
Alexander.

Quoting Kevin Widjaja <ke...@gm...> (from Sat, 4 Apr 2009  
14:44:01 -0700):

> Hi,
>
> I was wondering if you could help me with a technical question regarding mp3
> encoding.
>
> As far as I understand an mp3 file is divided into thousands of frames. Each
> frame with its own header that contains information such as bitrate,
> frequency, padding, etc.
>
> the formula for frame size is like so:
>
> frameSize = 144 * bitRate * 1000 / (frequency + padding); //in bytes
>
> this results in Frame Size in bytes.
>
> what I want to know is how do I translate this frame size into length in
> time? I'm thinking that
>
> time length = frameSize * 8 / bitrate
>
> this results in time length in milliseconds. is this correct?
>
> For example, if I have a frame with these specs:
> Bitrate: 128 kilobits per second
> Frequency: 44100
> Padding = 0
> Then framesize = 144 * 128,000 / 44,100 = 417 bytes.
>
> Then time length for this frame = 417 * 8 / 128,000 = 26 milliseconds.
>
> Is this correct?
>
> Thank you!
>



-- 
I've looked at the listing, and it's right!
		-- Joel Halpern

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