Changes between Initial Version and Version 1 of Ticket #10514


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Timestamp:
Aug 10, 2023, 2:46:07 PM (3 years ago)
Author:
vkonovets
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  • Ticket #10514 – Description

    initial v1  
    1 I'm working on an API which wraps around `swscale` to do conversions on memory not strictly allocated for `AVFrame` (i.e my own allocations).  For some image dimensions I noticed visual artifacts and memory corruption.  Although there are no alignment requirements for rows stated in the documentation, reading from Stack Overflow and various tickets here I understood that there is a minimum alignment requirement for allocations and padding padding at the end of the row (although this does not solve the issue).
     1I'm working on an API which wraps around `swscale` to do conversions on memory not strictly allocated for `AVFrame` (i.e my own allocations).  For some image dimensions I noticed visual artifacts and memory corruption.  Although there are no alignment requirements for rows stated in the documentation, reading from Stack Overflow and various tickets here I understood that there is a minimum alignment requirement for allocations and padding at the end of the row (although this does not solve the issue).
    22
    33https://trac.ffmpeg.org/ticket/9331 points out what I believe is the issue, however that ticket was dismissed because the memory allocation was not aligned (I ensure it is in my sample).  To quote:
    … …  
    106106- `get_video_buffer()` pads the height during allocation.  Why is this necessary?  Is this to do with `swscale` or another component of `libav`?
    107107- Are there padding requirements for grayscale, grayscale+alpha, RGBA formats?
    108 - Is there some source I could refer to for alignment requirements on memory (forum posts, tickets, documentation)?
     108- Is there some source I could refer to for alignment requirements on memory (forum posts, tickets, documentation) for any generic input/output pixel format?