[FFmpeg-devel] [RFC][PATCH 1/4] avutil/frame: add an internal field to store the size of AVFrame

[Andreas Rheinhardt]

James Almer:
> This is unfortunately needed to remove (or reduce the awfulness) of certain
> modules violating the AVFrame API and using sizeof(AVFrame).
> With this, the sizeof(AVFrame) value of the libavutil loaded at runtime can be
> used instead of the compile time value of whatever library included frame.h
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> This is sucks, but at least less so than the current situation.
> 
> I don't see wrapped_avframe going away anytime soon, so something must be done,
> and last time i tried to change how the packets are generated my approach was
> shut down, so here's another attempt.
> 

Where can I find this earlier approach?
(Also why don't we just switch to something like what is done for
uncoded frames in libavformat/mux.c?)

>  libavutil/frame.c          |  3 +++
>  libavutil/frame_internal.h | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+)
>  create mode 100644 libavutil/frame_internal.h
> 
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index 8997c85e35..a63d2979db 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -23,6 +23,7 @@
>  #include "cpu.h"
>  #include "dict.h"
>  #include "frame.h"
> +#include "frame_internal.h"
>  #include "imgutils.h"
>  #include "mem.h"
>  #include "samplefmt.h"
> @@ -33,6 +34,8 @@
>                 (frame)->channels == \
>                 av_get_channel_layout_nb_channels((frame)->channel_layout))
>  
> +const size_t avpriv_avframe_size = sizeof(AVFrame);
> +
>  #if FF_API_COLORSPACE_NAME
>  const char *av_get_colorspace_name(enum AVColorSpace val)
>  {
> diff --git a/libavutil/frame_internal.h b/libavutil/frame_internal.h
> new file mode 100644
> index 0000000000..07c246f86a
> --- /dev/null
> +++ b/libavutil/frame_internal.h
> @@ -0,0 +1,33 @@
> +/*
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef AVUTIL_FRAME_INTERNAL_H
> +#define AVUTIL_FRAME_INTERNAL_H
> +
> +#include <stdint.h>
> +
> +#include "frame.h"

This header is completely unnecessary.

> +
> +/**
> + * sizeof(AVFrame). If you think you need to use it, then you need to change
> + * your code so you don't instead.
> + * Meant for exceptions like wrapped_avframe.
> + */
> +extern const size_t avpriv_avframe_size;
> +
> +#endif /* AVUTIL_FRAME_INTERNAL_H */