On Sun, Aug 16, 2020 at 10:57:26PM +0200, Alexander Strasser wrote: > On 2020-08-13 22:32 +0200, Michael Niedermayer wrote: > > On Wed, Aug 12, 2020 at 08:58:30PM +0200, Alexander Strasser wrote: > > > On 2020-08-09 14:56 +0200, Michael Niedermayer wrote: > [...] > > > > > > > > lib user > > > > > > > > > If I'm not mistaken, a library user should not set it to NULL. Is it > > > > > even possible while respecting public API? > > > > > > > > if its not possible then the patch should be fine. I was just asking > > > > becasue > > > > thats the thing that would change if it can be set > > > > > > The rc_eq field was removed from AVCodecContext with the merge > > > commit bfab430856 and lives only inside private contexts these > > > days. > > > > > > Now I'm not 100% sure if there is a way to use av_opt API to set a > > > string type option's value to NULL. Though it would worry me if that > > > is possible, even for options that have a default string. > > > > > > If you know about that, I would be grateful to hear. Will see > > > if I can it try out myself too. > > > > One can probably do it (maybe with av_opt_ptr()) how realistic an > > issue this is, i dont know. > > > > For the future we should ensure though its clearly documented if > > NULL is valid for AV_OPT_TYPE_STRING because part of the issue > > here is i think its not clearly documented if this is allowed > > Unfortunately I think ATM it is always possible to set (unset?) a > string option to NULL with a simple av_set_opt call. > > I think in particular in combination with defaults this is problematic. > > I'm sure many places in our code don't expect a NULL for an > AV_OPT_TYPE_STRING field that has a default. > > What do you and others think about the matter? > How should we deal with this? > > As I see the situation, we could either decide > > 1. to fix a lot of places to handle NULL? > 2. to document for a lot of options that NULL is invalid > 3. to disallow > a) setting options to NULL > b) setting options to NULL if they have a non-NULL default > 4. to reset options to their defaults if they are set to NULL
Are there cases where NULL is needed ? If so, a flag that specifies that the value may be NULL could be a possibility too to seperate the fields that do not allow or support NULL vs the ones where it is needed and supported thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Republics decline into democracies and democracies degenerate into despotisms. -- Aristotle
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