[FFmpeg-devel] [PATCH] avutil/hwcontext_cuda: add AVCUDAFramesContext and AVCUDAFramesContext.flags

[Wang Bin]

2018-05-08 5:10 GMT+08:00 Timo Rothenpieler <timo at rothenpieler.org>:

> Frames can be mapped from nvdec/cuvid, not needing any actual memory
> allocation, but all other features of the hw_frames_ctx.
> Hence the dummy-mode, which does not allocate any (notable amounts of)
> memory but otherwise behaves the exact same.
> ---
>  doc/APIchanges             |  3 +++
>  libavutil/hwcontext_cuda.c | 10 ++++++++++
>  libavutil/hwcontext_cuda.h | 18 +++++++++++++++++-
>  libavutil/version.h        |  2 +-
>  4 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index ede5b186ae..82ec888fd8 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil:     2017-10-21
>
>  API changes, most recent first:
>
> +2018-05-xx - xxxxxxxxxx - lavu 56.19.100 - hwcontext.h
> +  Add AVCUDAFramesContext and AVCUDAFramesContext.flags.
> +
>  2018-04-xx - xxxxxxxxxx - lavu 56.18.100 - pixdesc.h
>    Add AV_PIX_FMT_FLAG_ALPHA to AV_PIX_FMT_PAL8.
>
> diff --git a/libavutil/hwcontext_cuda.c b/libavutil/hwcontext_cuda.c
> index 37827a770c..0d867ef0f5 100644
> --- a/libavutil/hwcontext_cuda.c
> +++ b/libavutil/hwcontext_cuda.c
> @@ -83,6 +83,7 @@ static void cuda_buffer_free(void *opaque, uint8_t *data)
>  static AVBufferRef *cuda_pool_alloc(void *opaque, int size)
>  {
>      AVHWFramesContext     *ctx = opaque;
> +    AVCUDAFramesContext *frctx = ctx->hwctx;
>      AVCUDADeviceContext *hwctx = ctx->device_ctx->hwctx;
>      CudaFunctions          *cu = hwctx->internal->cuda_dl;
>
> @@ -97,6 +98,10 @@ static AVBufferRef *cuda_pool_alloc(void *opaque, int
> size)
>          return NULL;
>      }
>
> +    // A lot of places expect the pointer to be !=NULL, so make minimum
> allocation instead.
> +    if (frctx->flags & AV_CUDA_HWFRAMES_DUMMY_MODE)
> +        size = 1;
> +
>      err = cu->cuMemAlloc(&data, size);
>      if (err != CUDA_SUCCESS)
>          goto fail;
> @@ -161,6 +166,7 @@ static int cuda_frames_init(AVHWFramesContext *ctx)
>
>  static int cuda_get_buffer(AVHWFramesContext *ctx, AVFrame *frame)
>  {
> +    AVCUDAFramesContext *frctx = ctx->hwctx;
>      int aligned_width;
>      int width_in_bytes = ctx->width;
>
> @@ -210,6 +216,9 @@ static int cuda_get_buffer(AVHWFramesContext *ctx,
> AVFrame *frame)
>      frame->width  = ctx->width;
>      frame->height = ctx->height;
>
> +    if (frctx->flags & AV_CUDA_HWFRAMES_DUMMY_MODE)
> +        frame->data[0] = frame->data[1] = frame->data[2] = NULL;
> +
>      return 0;
>  }
>
> @@ -402,6 +411,7 @@ const HWContextType ff_hwcontext_type_cuda = {
>      .name                 = "CUDA",
>
>      .device_hwctx_size    = sizeof(AVCUDADeviceContext),
> +    .frames_hwctx_size    = sizeof(AVCUDAFramesContext),
>      .frames_priv_size     = sizeof(CUDAFramesContext),
>
>      .device_create        = cuda_device_create,
> diff --git a/libavutil/hwcontext_cuda.h b/libavutil/hwcontext_cuda.h
> index 12dae8449e..388d6f8f1c 100644
> --- a/libavutil/hwcontext_cuda.h
> +++ b/libavutil/hwcontext_cuda.h
> @@ -45,7 +45,23 @@ typedef struct AVCUDADeviceContext {
>  } AVCUDADeviceContext;
>
>  /**
> - * AVHWFramesContext.hwctx is currently not used
> + * This struct is allocated as AVHWFramesContext.hwctx
>   */
> +typedef struct AVCUDAFramesContext {
> +    /**
> +     * Special implementation-specific flags.
> +     *
> +     * Must be set by the user before calling av_hwframe_ctx_init().
> +     */
> +    int flags;
> +} AVCUDAFramesContext;
> +
> +/**
> + * No actual allocation will happen, but otherwise behaves like normal.
> + *
> + * This is to be used if a AVHWFramesContext is required, but the actual
> + * allocation has to happen outside of it.
> + */
> +#define AV_CUDA_HWFRAMES_DUMMY_MODE (1 << 0)
>
>  #endif /* AVUTIL_HWCONTEXT_CUDA_H */
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 5185454d9b..84409b1d69 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>   */
>
>  #define LIBAVUTIL_VERSION_MAJOR  56
> -#define LIBAVUTIL_VERSION_MINOR  18
> +#define LIBAVUTIL_VERSION_MINOR  19
>  #define LIBAVUTIL_VERSION_MICRO 100
>
>  #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
> --
>

I think the flag should be added in avcodec, maybe AVCodecContext.flags2,
becuase
1. This flag is used by cuda decoder only, but not works avfilter and other
cuda apis.
2. Other hw codecs may support referencing the decoded memory instead of
copying it, for example, mmal decoder. see
https://github.com/wang-bin/FFmpeg/commit/74390ec836743dd337c92dd5da5f4f9ff638316b#diff-26a23a40f16babe0068c7340c6160472
3. the flag can be turned on/off at any time