[M4IF Technotes] questions on mp4 file format

[Dave Singer]

At 12:26 -0800 2/6/02, Heat Mist wrote:
>On the MPEG4 FAQ, it is written that quicktime format
>is the start point of the mp4 file format. So what
>exactly is the difference between quicktime format and
>mp4 file format in term of the parsing I described in
>the previous email?

Minor differences.  For example, there is now an IOD in an atom; 
QuickTime had data handlers, which it no longer needs, and so they 
are dropped.
>If I have a quicktime parser that
>can extract out description information of the video,
>can it do the same thing on a mp4 file?

Yes, the sample description (which in MPEG-4 contains an ESD) is in 
the same place.
>
>Thanks,
>cft
>
>--- Rob Koenen <rkoenen   intertrust.com> wrote:
>>  -----Original Message-----
>>  From: Dave Singer [mailto:singer   apple.com]
>>  Sent: Wednesday, February 06, 2024 11:39
>>  To: Rob Koenen
>>  Subject: Re: FW: [M4IF Technotes] questions on mp4
>>  file format
>>
>>
>>  Yes, the meta-data and structure parsing is uniform;
>>   there are no
>>  profiles of the structure of the file format.  In
>>  addition, finding
>>  both the Initial Object Descriptor and all the
>>  Elementary Stream
>>  Descriptors is easy, and so it should be easy to
>>  determine whether
>>  you can decode the media data.
>>
>>  > -----Original Message-----
>>  > From: Heat Mist [mailto:heat_mist   yahoo.com]
>>  > Sent: Wednesday, February 06, 2024 9:08
>>  > To: technotes   lists.m4if.org
>>  > Subject: [M4IF Technotes] questions on mp4 file
>>  format
>>  >
>>  >
>>  > Hi,
>>  >
>>  > I understand that different mpeg4 encoders and
>>  > decoders can implement different video/audio
>>  profiles
>>  > of the standard so that mp4 file encoded by one
>>  > encoder may not be decoded by another decoder. Is
>>  it
>>  > possible to have a mp4 file parser that only
>>  retrieve
>>  > metadata information from any mp4 file without
>>  > decoding the data since the mp4 file structure
>>  should
>>  > be the same for every mp4 file?
>>  >
>>  > Thanks,
>>  >
>>  > cft
>>  >
>>  >
>>  >
>>  >
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>
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-- 
David Singer
Apple Computer/QuickTime