[Mp4-tech] (no subject)

[Dave Singer]

The fields you mention below actually document the encoded width and 
height for only one possible coding system.
The visual sample entry width and height document the encoded width 
and height in a general way.
The track width and height document that track's presentation width 
and height (normally the same as the encoded size).
The movie width and height is the bounding box of all visual tracks.
The bit-rate may be in the esds or the mpeg-4 bit-rate box;  you can 
also calculate it from the sample size box and the time-to-sample 
box, of course.
At 9:51  +0530 31/08/06, Shankar Jayaraman wrote:
>Adam,
>I'm giving pointers to the specific fields that you require.
>The bitrate, width and height of the movie can be obtained from the 
>'esds' atom of the Video Track.
>Look for the fields maxBitRate, avgBitRate, video_object_layer_width 
>and video_object_layer_height within this atom.
>
>Thanks,
>Shankar.
>
>
>>  ----- Original Message -----  From: Adam Potolsky
>>  To: Mp4-Tech Mailing List
>>  Sent: Wednesday, August 30, 2023 12:50 AM
>>  Subject: [Mp4-tech] (no subject)
>>
>>
>>  Good day,
>>
>>
>>
>>  I am in the process of creating some code to gather various forms 
>>of data from MP4 files, as well as, mpeg4 media content. Thus far I 
>>have been successful in parsing boxes to gather information like 
>>the title of the content (if present), etc. The difficulty I am 
>>having now is in trying to get more technical information such as 
>>the bitrate, and the height and width of a movie. Through my 
>>searches I have not found a source that describes how this kind of 
>>data can be extracted from a file. I assume it's inside the 'mdat' 
>>box data, but trying to figure out what to expect there form the 
>>thousands of pages of reference I have is very difficult. I have 
>>also looked through several source code solutions and they have 
>>been quite difficult to understand as they have lacked good source 
>>level comments and are not self documenting.
>>
>>
>>
>>  Is there a good source for this kind of information? Or, 
>>alternately, can anyone key me off to what I'm missing about how to 
>>read the various specs and code I have? (I have ISO/IEC 14496-lots, 
>>The MPEG Handbook, mplayer, the reference source from ISO, and 
>>more.)
>>
>>
>>
>>  Thank you very much in advance for any help you can be.
>>
>>  Adam Potolsky
>>
>
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-- 
David Singer
Apple Computer/QuickTime