[Mp4-tech] 'version' in mvhd atom in mp4 file

[Dave Singer]

At 12:10 PM +0000 8/26/04, MRUKANT POPAT wrote:
>
>hi all,
>
>The MOVIEHEADER atom 'mvhd' had following syntax in 14496-1 on page 
>266 of specification.
>----------------------------------------------------
>aligned(8) class MovieHeaderAtom (unsigned int(32) version) extends 
>FullAtom( mvhd , version, 0)
>{
>   if (version==1)
>   {
>     unsigned int(64) creation-time;
>     unsigned int(64) modification-time;
>     unsigned int(32) timescale;
>     unsigned int(64) duration;
>   }
>   else
>   { // version==0
>     unsigned int(32) creation-time;
>     unsigned int(32) modification-time;
>     unsigned int(32) timescale;
>     unsigned int(32) duration;
>   }
>   const bit(32)reserved = 0x00010000;
>   const bit(16)reserved = 0x0100;
>   const bit(16)reserved = 0;
>   const unsigned int(32)[2] reserved = 0;
>   const bit(32)[9] reserved = { 0x00010000, 0, 0, 0, 0x00010000, 0, 
>0, 0, 0x40000000 };
>   const bit(32)[6] reserved = 0;
>   unsigned int(32) next-track-ID;
>}
>----------------------------------------------
>
>looking at the first line of SDL (syntatic definition language), it 
>declares 'version' of 32 bits [unsigned int(32) version], which I 
>think is a typo, because version is used to check if other 
>data-fields are 64 bits or 32 bits inside the mvhd atom and that 
>'version' is part of definition of 'FullAtom' which ('version') is 8 
>bits in size.
>
>Can any one comment on it.
>
>regards,
>MRUKANT

this looks like an error;  it's not there in part 12:
aligned(8) class MovieHeaderBox extends FullBox('mvhd', version, 0) {
>
>
>
><http://clients.rediff.com/signature/track_sig.asp>
>
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-- 
David Singer
Apple Computer/QuickTime
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