Hi Niklas On Thu, Jul 24, 2025 at 01:11:54PM +0200, Niklas Haas wrote: > On Wed, 23 Jul 2025 19:02:06 +0200 Nicolas George wrote: > > Niklas Haas (HE12025-07-23): > > > [PATCH v2 05/18] avcodec/encode: enforce alpha mode compatibility at encode time > > > > That handles it for encoders, I suppose. But I do not see anything > > protecting you from stacking images with different kind of alpha or > > sending this kind of frames to a muxer with uncoded frames. > > That is no worse than the status quo, so I fail to see how this patch is > a regression in this regard. > > That aside, there is also not anything preventing you from doing the same > for images with a different chroma sample location, or different HDR metadata, > or different sample aspect ratios, or any of the other oodles of properties > (including arbitrarily extensible frame side data) that are not currently > participating in libavfilter format negotiation. > > In a perfect world, we would have automatic format negotiation for every > AVFrame property; but as it stands, the libavfilter code is too obnoxious, > brittle and inflexible to permit such while remaining sane. While redesigning > libavfilter to make it more extensible would certainly be a useful exercise > (perhaps a good STF 2025 candidate?), I think that rather exceeds the scope > of this patchset. About STF, it depends on who does the work. If a FFmpeg developer does the work, then i think STF is a good idea. OTOH It would be an inappropriate task for a new contributor (like in GSoC). One thing thats important for this is that whoever wants to work on this speaks with Nicolas to make sure theres agreement on the implementation. Because i belive everyone of us has a different idea how to implement this. My original plan was based on arbitrary graphs and a solution that could be proofen to be within a constant factor of the global optimum. This would have required simplifying the graph iteratively with a random seed multiple times IIRC. But because a single pass "just worked" i never implemented this. thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Democracy is the form of government in which you can choose your dictator