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

[Ryan Lei]

Please read 14496-12 for file format. Yes, version is 8 bits. It is correct
in 14496-12.
After 14496-1 was published, there are several Technical Corrigendum have
been published
to correct errors in 14496-1.
The best way to verify is to open a .mp4 file in a hex editor, if you don't
have other 
analyzer.
Ryan Lei, Ph.D
ATI Technologies Inc.
Handheld Products Team
33 Commerce Valley Dr. East
1-905-8822600 ext 2712 (o)
www.discover.uottawa.ca/~leizj/
-----Original Message-----
From: MRUKANT POPAT [mailto:mrukant.popat rediffmail.com] 
Sent: Thursday, August 26, 2023 8:11 AM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] 'version' in mvhd atom in mp4 file
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
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