Re: [FFmpeg-devel] [PATCH] avcodec: add farbfeld encoder

[marcus <marcus@marcusspencer.xyz>]

On Monday, June 3rd, 2024 at 1:05 AM, Rémi Denis-Courmont <remi@remlab.net> wrote:

> 
> 
> 
> 
> Le 3 juin 2024 06:27:16 GMT+03:00, Marcus B Spencer marcus@marcusspencer.xyz a écrit :
> 
> > farbfeld is an uncompressed image format that is a part of suckless
> > tools (https://tools.suckless.org).
> > 
> > Its documentation is available at https://tools.suckless.org/farbfeld.
> > 
> > Add support for this image format in avcodec and update the image2
> > format accordingly.
> > 
> > Signed-off-by: Marcus B Spencer marcus@marcusspencer.xyz
> > ---
> > Changelog | 1 +
> > doc/general_contents.texi | 2 +
> > libavcodec/Makefile | 1 +
> > libavcodec/allcodecs.c | 1 +
> > libavcodec/codec_desc.c | 7 ++++
> > libavcodec/codec_id.h | 1 +
> > libavcodec/farbfeldenc.c | 84 +++++++++++++++++++++++++++++++++++++++
> > libavcodec/version.h | 2 +-
> > libavformat/img2.c | 1 +
> > libavformat/img2enc.c | 2 +-
> > 10 files changed, 100 insertions(+), 2 deletions(-)
> > create mode 100644 libavcodec/farbfeldenc.c
> 
> > diff --git a/libavcodec/farbfeldenc.c b/libavcodec/farbfeldenc.c
> > new file mode 100644
> > index 0000000000..e48eba680e
> > --- /dev/null
> > +++ b/libavcodec/farbfeldenc.c
> > @@ -0,0 +1,84 @@
> > +/*
> > + * Copyright (c) 2024 Marcus B Spencer marcus@marcusspencer.xyz
> > + *
> > + * Permission is hereby granted, free of charge, to any person obtaining a copy
> > + * of this software and associated documentation files (the “Software”), to
> > + * deal in the Software without restriction, including without limitation the
> > + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
> > + * sell copies of the Software, and to permit persons to whom the Software is
> > + * furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice shall be included in
> > + * all copies or substantial portions of the Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> > + * IN THE SOFTWARE.
> > + */
> > +
> > +#include "libavutil/imgutils.h"
> > +#include "codec_internal.h"
> > +#include "bytestream.h"
> > +#include "avcodec.h"
> > +#include "encode.h"
> > +
> > +#define HEADER_SIZE 16
> > +
> > +static int farbfeld_encode_frame(AVCodecContext *ctx, AVPacket *pkt,
> > + const AVFrame *p, int *got_packet)
> > +{
> > + int pkt_size = HEADER_SIZE + av_image_get_buffer_size(
> > + p->format,
> > + p->width,
> > + p->height,
> > + 1
> > + );
> > + uint8_t *buf;
> > + int ret;
> > +
> > + if (pkt_size < 0)
> > + return pkt_size;
> > +
> > + // 16 is the header size
> > + if ((ret = ff_get_encode_buffer(ctx, pkt, pkt_size, 0)) < 0)
> > + return ret;
> > +
> > + buf = pkt->data;
> > +
> > + bytestream_put_buffer(&buf, "farbfeld", 8);
> > +
> > + bytestream_put_be32(&buf, ctx->width);
> > + bytestream_put_be32(&buf, ctx->height);
> > +
> > + av_image_copy_to_buffer(
> > + buf,
> > + pkt_size - HEADER_SIZE,
> > + (const uint8_t **)p->data,
> 
> 
> Bogus cast / aliasing violation.

I thought qualifiers don't affect aliasing rules in C. Am I wrong?

> 
> > + p->linesize,
> > + p->format,
> > + p->width,
> > + p->height,
> > + 1
> > + );
> > +
> > + *got_packet = 1;
> > +
> > + return 0;
> > +}
> > +
> > +const FFCodec ff_farbfeld_encoder = {
> > + .p.name = "farbfeld",
> > + CODEC_LONG_NAME("farbfeld uncompressed image"),
> > + .p.type = AVMEDIA_TYPE_VIDEO,
> > + .p.id = AV_CODEC_ID_FARBFELD,
> > + .p.capabilities = AV_CODEC_CAP_DR1,
> > + FF_CODEC_ENCODE_CB(farbfeld_encode_frame),
> > + .p.pix_fmts = (const enum AVPixelFormat[]){
> > + AV_PIX_FMT_RGBA64BE,
> > + AV_PIX_FMT_NONE
> > + },
> > +};
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