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Please provide an overview of the MP4 format and how to cut its audio, [TOS #6: was "mp4 file cutter" in CD Hardware/Software]
post Jan 12 2013, 14:05
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I am working with mp4 file cutter.Could anyone please help me how to get the clear overview of mp4 format and how to cut them.
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post Jan 13 2013, 04:50
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"MP4" is too generic. Maybe you are thinking of such that only contain one audio (probably AAC) track ?
At first you have to understand MP4 format by reading spec. You have to work mainly with some mp4 "box" structure such as stts, stsc, stsz, and stco as well as actual media samples (data) which goes under mdat box. All of these are considered as index to actual media samples, therefore required to edit.

AAC has inter frame dependency by overlapped nature of MDCT (and bit-reservoir). Therefore, it needs some pre-rolling to start playback at some arbitrary point.
When you implement cutting, you have to take this into account.
You will also need some way to express priming/padding samples for gapless playback.

This post has been edited by nu774: Jan 13 2013, 05:00
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