[Mp4-tech] MPEG4 Systems.. VisualSampleEntry

[veni soc-soft.com]

it helped
:)

veni
enJOY life
-----Original Message-----
From: Dave Singer [mailto:singer apple.com]
Sent: Friday, October 08, 2023 11:58 PM
To: Veni Madhav Soni; mp4-tech lists.mpegif.org
Subject: Re: [Mp4-tech] MPEG4 Systems.. VisualSampleEntry
At 10:52 AM +0530 10/8/04, veni soc-soft.com wrote:
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Folks,
Can someone tell me about the mystery of VisualSampleEntry. In the specs
all fields are reserved with some values(useful one like height width
etc like quick time file format). Can anyone give me the exact
defination of VisualSampleEntry for mpeg4 video.
veni
enJOY life
class VisualSampleEntry(codingname) extends SampleEntry (codingname){
   unsigned int(16) pre_defined = 0;
       const unsigned int(16) reserved = 0;
    unsigned int(32)[3]     pre_defined = 0;
        unsigned int(16)        width;
  unsigned int(16)        height;
template unsigned int(32)       horizresolution = 0x00480000;   // 72
dpi
       template unsigned int(32)       vertresolution  = 0x00480000;
// 72 dpi
       const unsigned int(32)  reserved = 0;
   template unsigned int(16)       frame_count = 1;
        string[32]      compressorname;
template unsigned int(16)       depth = 0x0018;
int(16) pre_defined = -1;
}
class MP4VisualSampleEntry() extends VisualSampleEntry ('mp4v'){
        ESDBox  ES;
}
The fields width and height in the VisualSampleEntry and in the Track
Header Box shall be set to the pixel dimensions of the visual stream.
The esds box contains an ES Descriptor and so on;  the decoder config
descriptor is the VOL header etc. for the stream, without any trailing
end code sequence.
Hope this helps.
--
David Singer
Apple Computer/QuickTime
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