Re: [FFmpeg-devel] [PATCH 7/7] lavfi/metal: fix build with pre-10.11 deployment targets

[Aman Karmani <ffmpeg@tmm1.net>]

On Tue, Dec 21, 2021 at 4:15 PM rcombs <rcombs@rcombs.me> wrote:

> - Ensure the yadif .metal compiles when targeting any Metal runtime version
> - Use some preprocessor awkwardness to ensure Core Video's Metal-specific
>   functionality is exposed regardless of our deployment target (this works
>   around what seems to be an SDK header bug, filed as FB9816002)
> - Ensure all direct references to Metal functions and classes are gated
>   behind runtime version checks (this satisfies clang's deployment-target
>   violation warnings provided by -Wunguarded-availability).
> ---
>  libavfilter/metal/utils.h                     | 28 +++++++-
>  libavfilter/metal/vf_yadif_videotoolbox.metal | 11 ++-
>  libavfilter/vf_yadif_videotoolbox.m           | 67 ++++++++++++++++---
>  3 files changed, 94 insertions(+), 12 deletions(-)
>

Patchset LGTM. Thanks for your work on this.


>
> diff --git a/libavfilter/metal/utils.h b/libavfilter/metal/utils.h
> index bd0319f63c..7350d42a35 100644
> --- a/libavfilter/metal/utils.h
> +++ b/libavfilter/metal/utils.h
> @@ -20,16 +20,40 @@
>  #define AVFILTER_METAL_UTILS_H
>
>  #include <Metal/Metal.h>
> +
> +#include <AvailabilityMacros.h>
> +
> +// CoreVideo accidentally(?) preprocessor-gates Metal functionality
> +// on MAC_OS_X_VERSION_MIN_REQUIRED >= 101100 (FB9816002).
> +// There doesn't seem to be any particular reason for this,
> +// so here we temporarily redefine it to at least that value
> +// so CV will give us CVMetalTextureRef and the related functions.
> +
> +#if defined(MAC_OS_X_VERSION_MIN_REQUIRED) &&
> (MAC_OS_X_VERSION_MIN_REQUIRED < 101100)
> +#define ORIG_MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_MIN_REQUIRED
> +#undef MAC_OS_X_VERSION_MIN_REQUIRED
> +#define MAC_OS_X_VERSION_MIN_REQUIRED 101100
> +#endif
> +
>  #include <CoreVideo/CoreVideo.h>
>
> +#ifdef ORIG_MAC_OS_X_VERSION_MIN_REQUIRED
> +#undef MAC_OS_X_VERSION_MIN_REQUIRED
> +#define MAC_OS_X_VERSION_MIN_REQUIRED ORIG_MAC_OS_X_VERSION_MIN_REQUIRED
> +#undef ORIG_MAC_OS_X_VERSION_MIN_REQUIRED
> +#endif
> +
>  void ff_metal_compute_encoder_dispatch(id<MTLDevice> device,
>                                         id<MTLComputePipelineState>
> pipeline,
>                                         id<MTLComputeCommandEncoder>
> encoder,
> -                                       NSUInteger width, NSUInteger
> height);
> +                                       NSUInteger width, NSUInteger
> height)
> +                                       API_AVAILABLE(macos(10.11),
> ios(8.0));
>
>  CVMetalTextureRef ff_metal_texture_from_pixbuf(void *avclass,
>                                                 CVMetalTextureCacheRef
> textureCache,
>                                                 CVPixelBufferRef pixbuf,
>                                                 int plane,
> -                                               MTLPixelFormat format);
> +                                               MTLPixelFormat format)
> +
>  API_AVAILABLE(macos(10.11), ios(8.0));
> +
>  #endif /* AVFILTER_METAL_UTILS_H */
> diff --git a/libavfilter/metal/vf_yadif_videotoolbox.metal
> b/libavfilter/metal/vf_yadif_videotoolbox.metal
> index 50783f2ffe..8a3d41a30f 100644
> --- a/libavfilter/metal/vf_yadif_videotoolbox.metal
> +++ b/libavfilter/metal/vf_yadif_videotoolbox.metal
> @@ -26,6 +26,15 @@
>
>  using namespace metal;
>
> +/*
> + * Version compat shims
> + */
> +
> +#if __METAL_VERSION__ < 210
> +#define max3(x, y, z) max(x, max(y, z))
> +#define min3(x, y, z) min(x, min(y, z))
> +#endif
> +
>  /*
>   * Parameters
>   */
> @@ -44,7 +53,7 @@ struct deintParams {
>   */
>
>  #define accesstype access::sample
> -const sampler s(coord::pixel);
> +constexpr sampler s(coord::pixel);
>
>  template <typename T>
>  T tex2D(texture2d<float, access::sample> tex, uint x, uint y)
> diff --git a/libavfilter/vf_yadif_videotoolbox.m
> b/libavfilter/vf_yadif_videotoolbox.m
> index 65f155982e..455745817f 100644
> --- a/libavfilter/vf_yadif_videotoolbox.m
> +++ b/libavfilter/vf_yadif_videotoolbox.m
> @@ -26,10 +26,12 @@
>  #include "libavutil/hwcontext.h"
>  #include "libavutil/objc.h"
>
> +#include <assert.h>
> +
>  extern char ff_vf_yadif_videotoolbox_metallib_data[];
>  extern unsigned int ff_vf_yadif_videotoolbox_metallib_len;
>
> -typedef struct YADIFVTContext {
> +typedef struct API_AVAILABLE(macos(10.11), ios(8.0)) YADIFVTContext {
>      YADIFContext yadif;
>
>      AVBufferRef       *device_ref;
> @@ -44,7 +46,12 @@ typedef struct YADIFVTContext {
>      id<MTLBuffer> mtlParamsBuffer;
>
>      CVMetalTextureCacheRef textureCache;
> -} YADIFVTContext;
> +} YADIFVTContext API_AVAILABLE(macos(10.11), ios(8.0));
> +
> +// Using sizeof(YADIFVTContext) outside of an availability check will
> error
> +// if we're targeting an older OS version, so we need to calculate the
> size ourselves
> +// (we'll statically verify it's correct in yadif_videotoolbox_init
> behind a check)
> +#define YADIF_VT_CTX_SIZE (sizeof(YADIFContext) + sizeof(void*) * 10)
>
>  struct mtlYadifParams {
>      uint channels;
> @@ -62,7 +69,7 @@ static void call_kernel(AVFilterContext *ctx,
>                          id<MTLTexture> next,
>                          int channels,
>                          int parity,
> -                        int tff)
> +                        int tff) API_AVAILABLE(macos(10.11), ios(8.0))
>  {
>      YADIFVTContext *s = ctx->priv;
>      id<MTLCommandBuffer> buffer = s->mtlQueue.commandBuffer;
> @@ -93,7 +100,7 @@ static void call_kernel(AVFilterContext *ctx,
>  }
>
>  static void filter(AVFilterContext *ctx, AVFrame *dst,
> -                   int parity, int tff)
> +                   int parity, int tff) API_AVAILABLE(macos(10.11),
> ios(8.0))
>  {
>      YADIFVTContext *s = ctx->priv;
>      YADIFContext *y = &s->yadif;
> @@ -162,7 +169,7 @@ exit:
>      return;
>  }
>
> -static av_cold void yadif_videotoolbox_uninit(AVFilterContext *ctx)
> +static av_cold void do_uninit(AVFilterContext *ctx)
> API_AVAILABLE(macos(10.11), ios(8.0))
>  {
>      YADIFVTContext *s = ctx->priv;
>      YADIFContext *y = &s->yadif;
> @@ -188,7 +195,15 @@ static av_cold void
> yadif_videotoolbox_uninit(AVFilterContext *ctx)
>      }
>  }
>
> -static av_cold int yadif_videotoolbox_init(AVFilterContext *ctx)
> +
> +static av_cold void yadif_videotoolbox_uninit(AVFilterContext *ctx)
> +{
> +    if (@available(macOS 10.11, iOS 8.0, *)) {
> +        do_uninit(ctx);
> +    }
> +}
> +
> +static av_cold int do_init(AVFilterContext *ctx)
> API_AVAILABLE(macos(10.11), ios(8.0))
>  {
>      YADIFVTContext *s = ctx->priv;
>      NSError *err = nil;
> @@ -261,7 +276,19 @@ fail:
>      return AVERROR_EXTERNAL;
>  }
>
> -static int config_input(AVFilterLink *inlink)
> +static av_cold int yadif_videotoolbox_init(AVFilterContext *ctx)
> +{
> +    if (@available(macOS 10.11, iOS 8.0, *)) {
> +        // Ensure we calculated YADIF_VT_CTX_SIZE correctly
> +        static_assert(YADIF_VT_CTX_SIZE == sizeof(YADIFVTContext),
> "Incorrect YADIF_VT_CTX_SIZE value!");
> +        return do_init(ctx);
> +    } else {
> +        av_log(ctx, AV_LOG_ERROR, "Metal is not available on this OS
> version\n");
> +        return AVERROR(ENOSYS);
> +    }
> +}
> +
> +static int do_config_input(AVFilterLink *inlink)
> API_AVAILABLE(macos(10.11), ios(8.0))
>  {
>      AVFilterContext *ctx = inlink->dst;
>      YADIFVTContext *s = ctx->priv;
> @@ -283,7 +310,18 @@ static int config_input(AVFilterLink *inlink)
>      return 0;
>  }
>
> -static int config_output(AVFilterLink *link)
> +static int config_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    if (@available(macOS 10.11, iOS 8.0, *)) {
> +        return do_config_input(inlink);
> +    } else {
> +        av_log(ctx, AV_LOG_ERROR, "Metal is not available on this OS
> version\n");
> +        return AVERROR(ENOSYS);
> +    }
> +}
> +
> +static int do_config_output(AVFilterLink *link)
> API_AVAILABLE(macos(10.11), ios(8.0))
>  {
>      AVHWFramesContext *output_frames;
>      AVFilterContext *ctx = link->src;
> @@ -347,6 +385,17 @@ exit:
>      return ret;
>  }
>
> +static int config_output(AVFilterLink *link)
> +{
> +    AVFilterContext *ctx = link->src;
> +    if (@available(macOS 10.11, iOS 8.0, *)) {
> +        return do_config_output(link);
> +    } else {
> +        av_log(ctx, AV_LOG_ERROR, "Metal is not available on this OS
> version\n");
> +        return AVERROR(ENOSYS);
> +    }
> +}
> +
>  #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
>  #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST,
> {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }
>
> @@ -394,7 +443,7 @@ static const AVFilterPad yadif_videotoolbox_outputs[]
> = {
>  AVFilter ff_vf_yadif_videotoolbox = {
>      .name           = "yadif_videotoolbox",
>      .description    = NULL_IF_CONFIG_SMALL("YADIF for VideoToolbox frames
> using Metal compute"),
> -    .priv_size      = sizeof(YADIFVTContext),
> +    .priv_size      = YADIF_VT_CTX_SIZE,
>      .priv_class     = &yadif_videotoolbox_class,
>      .init           = yadif_videotoolbox_init,
>      .uninit         = yadif_videotoolbox_uninit,
> --
> 2.33.1
>
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