[FFmpeg-devel] [PATCH 5/6] Add support for V4L2 mem2mem codecs.

[Michael Niedermayer]

On Thu, Nov 20, 2014 at 05:51:56PM +0100, Alexis Ballier wrote:
> Default buffer settings should work with all drivers (mmaped memory from the driver) but would imply useless memcpy()'s if used in the standard way.
> libavcodec/v4l2.h is now installed to allow applications to get the proper buffers to avoid these copies.
> 
> This has been tested on MFC5, on a Samsung exynos 4412 SOC (odroid u3).
[...]
> +/**
> + * Sets the status of a V4LBufferPool.
> + *
> + * @param[in] bp A pointer to a V4LBufferPool.
> + * @param[in] cmd The status to set (VIDIOC_STREAMON or VIDIOC_STREAMOFF).
> + *                Warning: If VIDIOC_STREAMOFF is sent to a buffer pool that still has some frames buffered,
> + *                those frames will be dropped.
> + * @return 0 in case of success, a negative value representing the error otherwise.

in general ffmpeg uses larger or equal than 0 for success
the advantage of this is that we can use positive return values
to return some information in the future without breaking API/ABI


[...]
> diff --git a/libavcodec/v4l2.h b/libavcodec/v4l2.h
> new file mode 100644
> index 0000000..8771b4f
> --- /dev/null
> +++ b/libavcodec/v4l2.h
> @@ -0,0 +1,66 @@
> +/*
> + * V4L2 bufferpools helper functions
> + * Copyright (C) 2014 Alexis Ballier
> + *
> + * 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 AVCODEC_V4L2_H
> +#define AVCODEC_V4L2_H
> +

> +#include <libavutil/frame.h>
> +#include <libavcodec/avcodec.h>

we use #include "" in other installed headers

is it intentional that you dont use that form ?


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct answer.
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