[FFmpeg-devel] [PATCH 3/9] avformat/avisynth: add read_frameprops option

[Stephen Hutchinson]

On 8/28/22 8:41 PM, Andreas Rheinhardt wrote:
> This will make frameprops a global on-off which overrides everything
> else even if some of the "else" stuff has been enabled explicitly. Worse
> yet, if you want to disable everything except exactly one field, you
> have to leave frameprops enabled and disable everything else explicitly.
> 
> Why not use a bitfield (with AV_OPT_TYPE_FLAGS and AV_OPT_TYPE_CONST)?
> These properties certainly seem like a bitfield and the above would be
> easily achievable with it.
> 

How are flags supposed to be set to on by default? With av_dict_set or
a different mechanism?  Because the closest I was able to get¹,

if(avs->flags & AVISYNTH_FRAMEPROP_FIELD_ORDER | 
AVISYNTH_FRAMEPROP_DEFAULT) {

ends up correctly setting the flags that should be on by default,
with the new sar flag able to be enabled or disabled, but the ones
flagged as default refuse to be disabled now.

¹https://github.com/qyot27/FFmpeg/commit/6d3d6108145f9c7ac2dfcdaf09852b7472f6ca7f