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Topic: what does MP3 frame size include? (Read 6070 times) previous topic - next topic
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what does MP3 frame size include?

I am a MP3 newbie and trying to understand how to go about parsing out "true" audio data bytes from a MP3 file.
I have come to a understanding that a mp3 frame consists of a frame header and data
and within the frame header itself, it can have headers like XING, LAME, VBRI.
I am wondering if the frame size that can calculated after parsing the 4-byte frame header

(i.e. Frame Size = ( (Samples Per Frame / 8 * Bitrate) / Sampling Rate) + Padding Size)

include these extra header(XING, VBRI, etc) bytes.
And also how about optional CRC bytes?

So all in all, my question is what does "frame size" represent?


what does MP3 frame size include?

Reply #1 –
Quote from: wonderfuljames on
include these extra header(XING, VBRI, etc) bytes.


No because those headers (if present) are only once per file before the start of the audio data and are not included in each and every frame.

Quote from: wonderfuljames on
So all in all, my question is what does "frame size" represent?


Exactly what it sounds like:  the number of bytes in one frame.

what does MP3 frame size include?

Reply #2 –
Quote from: saratoga on
Quote from: wonderfuljames on
include these extra header(XING, VBRI, etc) bytes.


No because those headers (if present) are only once per file before the start of the audio data and are not included in each and every frame.

Quote from: wonderfuljames on
So all in all, my question is what does "frame size" represent?


Exactly what it sounds like:  the number of bytes in one frame.


Thanks for your reply.
I was talking about the frame size of a frame that includes XING, LAME, VBRI at the start.
Not the ones that don't include those headers.

what does MP3 frame size include?

Reply #3 –
I don't think the calculation is any different.