On Fri, May 6, 2022 at 3:11 AM Soft Works <softwo...@hotmail.com> wrote: > > > > > -----Original Message----- > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of Wu, > > Tong1 > > Sent: Thursday, May 5, 2022 11:50 AM > > To: FFmpeg development discussions and patches <ffmpeg- > > de...@ffmpeg.org> > > Subject: Re: [FFmpeg-devel] [PATCH v2 1/5] avutil/hwcontext_d3d11va: > > fix the uninitialized texture bindflag > > > > > > -----Original Message----- > > > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of > > > > Hendrik Leppkes > > > > Sent: Sunday, May 1, 2022 5:54 PM > > > > To: FFmpeg development discussions and patches <ffmpeg- > > > > de...@ffmpeg.org> > > > > Subject: Re: [FFmpeg-devel] [PATCH v2 1/5] > > avutil/hwcontext_d3d11va: > > > > fix the uninitialized texture bindflag > > > > > > > > On Sun, May 1, 2022 at 5:48 PM Hendrik Leppkes > > <h.lepp...@gmail.com> > > > > wrote: > > > > > > > > > > On Sun, May 1, 2022 at 7:09 AM Soft Works > > <softwo...@hotmail.com> > > > > wrote: > > > > > > I think that's what Hendrik wanted to point out as far as I > > > > understood. > > > > > > > > > > > > > > > > Basically, I want explicit behavior, not implicit defaults. > > Anytime > > > > a > > > > > hwcontext is created, something should tell it what its going to > > be > > > > > used for, so we can determine which flags make sense (or > > ideally, it > > > > > should just specify the flags). > > > > > > > > > > This patch creates an implicit default for one use-case, is this > > > > going > > > > > to work with all others? No, of course not, because it has to > > know > > > > > what flags to set. Thats why explicitly setting those flags is > > > > > important, instead of just fixing one implicit case. > > > > > > I said I agree with you - basically, just that we need to > > differentiate between > > > the use case: > > > > > > 1. Use via API > > > => No defaults should be applied, caller is responsible for > > specifying > > > the flags > > > > > > 2. Use via ffmpeg cli > > > => Applying the render target flag would be safe here. > > > We could require this to set via parameter, but there won't > > ever > > > be a case to specify something different than the render > > target flag > > > > > > Why? Let's look at the possible flags: > > > > > > D3D11_BIND_DECODER > > > In all decoding cases, this flag is set explicitly, so it overrides > > any default we > > > would set > > > > > > D3D11_BIND_VIDEO_ENCODER > > > Set explicitly when required, so it overrides any default we would > > set > > > > > > D3D11_BIND_RENDER_TARGET > > > All other cases require this flag (e.g. video processing) > > > > > > No Flag > > > Dead end, texture would be unusable for any kind of video processing > > > > > > > > > > On that note, the example commandline it fixes just does hwupload > > and > > > > nothing else - does that even require render target to be flagged? > > > > From what I can tell it uses a simple > > > > ID3D11DeviceContext::CopySubresourceRegion to copy from the > > staging > > > > texture, which should not require any particular bind flags. Bind > > > > Flags in turn would then depend on what you are actually trying to > > do > > > > with the texture (shader input, etc), in this example... nothing? > > > > > > We are still in the context of ffmpeg cli - you know that there are > > no shaders > > > or 3d operations and no etc. > > > > > > But at this point, you can derive to another context or you can > > hwmap. > > > For all of those things, you need D3D11_BIND_RENDER_TARGET. > > > > > > > > > Summary > > > > > > As mentioned I see two possibilities: > > > > > > 1. Use D3D11_BIND_RENDER_TARGET as a default when used in context of > > > ffmpeg cli, otherwise no default flags > > > > > > 2. Require a device initialization parameter in the command line > > > (but it would always be about setting the render target flag > > > and there's no case where you would NOT want to set it) > > > > > > > Thanks for the possible solutions for this issue. The No.1 seems more > > reasonable because > > No.2 just seems more unnecessary. But I will still need to find a > > better place to set the flag. > > I would favor #1 as well. > > Regarding "better place to set the flag": > > The BindFlag needs to be set when initializing a FRAMES context. > But at this point, there's no way to determine whether the code is running > in an ffmpeg cli process or used by an API consumer. > > But there would be an opportunity to convey this information on > device init. The device (D3D11VA) could then set an internal flag > from device init and use this on frames init to determine which default > to use for the BindFlags value. > > Remains the question how ffmpeg cli can convey this information to > the device (for use during device init). > > What I thought would be to have ffmpeg.c (or rather ffmpeg_hw.c) > to ALWAYS (for all hwaccels) add an entry to the options dictionary, > something like "cli" or similar. > This would avoid introducing a "special-case" mechanism just for > this case (=> by making it a common behavior). > > There are other cases where this might be useful in order to > discriminate API usage from cli usage. > > But let's see what the others think first.. >
Think of the CLI applications as an API user, and design for that, because thats really what they are, and thats how you actually end up with a good API that covers more cases. If special CLI logic is needed, it should be in the CLI applications, and not in the libraries. - Hendrik _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
