• Andreas Rheinhardt's avatar
    avfilter/avfilter: Add numbers of (in|out)pads directly to AVFilter · 8be701d9
    Andreas Rheinhardt authored
    Up until now, an AVFilter's lists of input and output AVFilterPads
    were terminated by a sentinel and the only way to get the length
    of these lists was by using avfilter_pad_count(). This has two
    drawbacks: first, sizeof(AVFilterPad) is not negligible
    (i.e. 64B on 64bit systems); second, getting the size involves
    a function call instead of just reading the data.
    
    This commit therefore changes this. The sentinels are removed and new
    private fields nb_inputs and nb_outputs are added to AVFilter that
    contain the number of elements of the respective AVFilterPad array.
    
    Given that AVFilter.(in|out)puts are the only arrays of zero-terminated
    AVFilterPads an API user has access to (AVFilterContext.(in|out)put_pads
    are not zero-terminated and they already have a size field) the argument
    to avfilter_pad_count() is always one of these lists, so it just has to
    find the filter the list belongs to and read said number. This is slower
    than before, but a replacement function that just reads the internal numbers
    that users are expected to switch to will be added soon; and furthermore,
    avfilter_pad_count() is probably never called in hot loops anyway.
    
    This saves about 49KiB from the binary; notice that these sentinels are
    not in .bss despite being zeroed: they are in .data.rel.ro due to the
    non-sentinels.
    Reviewed-by: 's avatarNicolas George <george@nsup.org>
    Signed-off-by: 's avatarAndreas Rheinhardt <andreas.rheinhardt@outlook.com>
    8be701d9
vf_field.c 3.5 KB