Re: [FFmpeg-devel] [PATCH v21] avformat: add farbfeld muxer and demuxer

[Ramiro Polla <ramiro.polla@gmail.com>]

On Fri, Jul 12, 2024 at 3:53 PM Marcus B Spencer
<marcus@marcusspencer.xyz> wrote:
>
> 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 avformat.
>
> Signed-off-by: Marcus B Spencer <marcus@marcusspencer.xyz>
> ---
> Remove unnecessary loop variable from FarbfeldDemuxContext.
>
>  Changelog                 |   1 +
>  doc/general_contents.texi |   4 +
>  libavformat/Makefile      |   2 +
>  libavformat/allformats.c  |   4 +-
>  libavformat/farbfelddec.c | 133 +++++++++++++++++++++++++++++++++
>  libavformat/farbfeldenc.c | 151 ++++++++++++++++++++++++++++++++++++++
>  libavformat/version.h     |   4 +-
>  7 files changed, 296 insertions(+), 3 deletions(-)
>  create mode 100644 libavformat/farbfelddec.c
>  create mode 100644 libavformat/farbfeldenc.c
>
> diff --git a/Changelog b/Changelog
> index 3708e35a2a..10f2b1e239 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -17,6 +17,7 @@ version <next>:
>  - perlin video source
>  - D3D12VA HEVC encoder
>  - Cropping metadata parsing and writing in Matroska and MP4/MOV de/muxers
> +- farbfeld muxer and demuxer
>
>  version 7.0:
>  - DXV DXT1 encoder
> diff --git a/doc/general_contents.texi b/doc/general_contents.texi
> index e7cf4f8239..bbc49d3665 100644
> --- a/doc/general_contents.texi
> +++ b/doc/general_contents.texi
> @@ -489,6 +489,8 @@ library:
>  @item Electronic Arts Multimedia  @tab    @tab X
>      @tab Used in various EA games; files have extensions like WVE and UV2.
>  @item Ensoniq Paris Audio File  @tab   @tab X
> +@item FF                        @tab X @tab X
> +    @tab farbfeld uncompressed image
>  @item FFM (FFserver live feed)  @tab X @tab X
>  @item Flash (SWF)               @tab X @tab X
>  @item Flash 9 (AVM2)            @tab X @tab X
> @@ -786,6 +788,8 @@ following image formats are supported:
>      @tab Digital Picture Exchange
>  @item EXR          @tab   @tab X
>      @tab OpenEXR
> +@item FF           @tab X @tab X
> +    @tab farbfeld uncompressed image
>  @item FITS         @tab X @tab X
>      @tab Flexible Image Transport System
>  @item HDR          @tab X @tab X
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 7ca68a7036..e2bf420916 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -284,6 +284,8 @@ OBJS-$(CONFIG_IMAGE_CRI_PIPE_DEMUXER)     += img2dec.o img2.o
>  OBJS-$(CONFIG_IMAGE_DDS_PIPE_DEMUXER)     += img2dec.o img2.o
>  OBJS-$(CONFIG_IMAGE_DPX_PIPE_DEMUXER)     += img2dec.o img2.o
>  OBJS-$(CONFIG_IMAGE_EXR_PIPE_DEMUXER)     += img2dec.o img2.o
> +OBJS-$(CONFIG_IMAGE_FARBFELD_PIPE_DEMUXER)+= farbfelddec.o
> +OBJS-$(CONFIG_IMAGE_FARBFELD_MUXER)       += farbfeldenc.o
>  OBJS-$(CONFIG_IMAGE_GEM_PIPE_DEMUXER)     += img2dec.o img2.o
>  OBJS-$(CONFIG_IMAGE_GIF_PIPE_DEMUXER)     += img2dec.o img2.o
>  OBJS-$(CONFIG_IMAGE_HDR_PIPE_DEMUXER)     += img2dec.o img2.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 305fa46532..01a9ef92e5 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -531,12 +531,14 @@ extern const FFInputFormat  ff_xwma_demuxer;
>  extern const FFInputFormat  ff_yop_demuxer;
>  extern const FFInputFormat  ff_yuv4mpegpipe_demuxer;
>  extern const FFOutputFormat ff_yuv4mpegpipe_muxer;
> -/* image demuxers */
> +/* image (de)muxers */
>  extern const FFInputFormat  ff_image_bmp_pipe_demuxer;
>  extern const FFInputFormat  ff_image_cri_pipe_demuxer;
>  extern const FFInputFormat  ff_image_dds_pipe_demuxer;
>  extern const FFInputFormat  ff_image_dpx_pipe_demuxer;
>  extern const FFInputFormat  ff_image_exr_pipe_demuxer;
> +extern const FFInputFormat  ff_image_farbfeld_pipe_demuxer;
> +extern const FFOutputFormat ff_image_farbfeld_muxer;
>  extern const FFInputFormat  ff_image_gem_pipe_demuxer;
>  extern const FFInputFormat  ff_image_gif_pipe_demuxer;
>  extern const FFInputFormat  ff_image_hdr_pipe_demuxer;
> diff --git a/libavformat/farbfelddec.c b/libavformat/farbfelddec.c
> new file mode 100644
> index 0000000000..41361e771b
> --- /dev/null
> +++ b/libavformat/farbfelddec.c
> @@ -0,0 +1,133 @@
> +/*
> + * Image format
> + * YUV4MPEG demuxer
> + *
> + * Modified by Marcus B Spencer to suit the farbfeld_pipe demuxer on 12 July 2024
> + *
> + * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
> + * Copyright (c) 2001, 2002, 2003 Fabrice Bellard
> + * Copyright (c) 2004 Michael Niedermayer
> + * Copyright (c) 2024 Marcus B Spencer
> + *
> + * 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
> + */
> +
> +#include "avformat.h"
> +#include "avio.h"
> +#include "demux.h"
> +#include "internal.h"
> +#include "libavutil/imgutils.h"
> +#include "libavutil/opt.h"
> +
> +#define FARBFELD_MAGIC_LEN 8
> +#define FARBFELD_HEADER_LEN (8 + 4 + 4)
> +
> +typedef struct FarbfeldDemuxContext {
> +    const AVClass *class;
> +    AVRational framerate;
> +} FarbfeldDemuxContext;
> +
> +static int farbfeld_read_header(AVFormatContext *ctx)
> +{
> +    FarbfeldDemuxContext *priv = ctx->priv_data;
> +    char magic[FARBFELD_MAGIC_LEN];
> +    int width, height;
> +    AVStream *st;
> +    int ret;
> +
> +    if ((ret = avio_read(ctx->pb, magic, FARBFELD_MAGIC_LEN)) < 0)
> +        return ret;
> +
> +    if (memcmp(magic, "farbfeld", FARBFELD_MAGIC_LEN))
> +        return AVERROR_INVALIDDATA;
> +
> +    if (!(st = avformat_new_stream(ctx, NULL)))
> +        return AVERROR(ENOMEM);
> +
> +    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
> +    st->codecpar->format     = AV_PIX_FMT_RGBA64BE;
> +    st->codecpar->codec_id   = AV_CODEC_ID_RAWVIDEO;
> +
> +    width  = avio_rb32(ctx->pb);
> +    height = avio_rb32(ctx->pb);
> +
> +    st->codecpar->width     = width;
> +    st->codecpar->height    = height;
> +    st->codecpar->framerate =
> +    st->avg_frame_rate      =
> +    st->r_frame_rate        = priv->framerate;

> +    ctx->packet_size = av_image_get_buffer_size(st->codecpar->format, width, height, 1) + FARBFELD_HEADER_LEN;
> +    if ((int)ctx->packet_size < 0)
> +        return ctx->packet_size;

int packet_size;
[...]
packet_size = av_image_get_buffer_size(st->codecpar->format, width, height, 1);
if (packet_size < 0)
    return AVERROR_INVALIDDATA;
ctx->packet_size = FARBFELD_HEADER_LEN + packet_size;

> +    // reset position for inital packet
> +    if ((ret = avio_seek(ctx->pb, 0, SEEK_SET)) < 0)
> +        return ret;
> +
> +    return 0;
> +}
> +
> +static int farbfeld_read_packet(AVFormatContext *ctx, AVPacket *pkt)
> +{
> +    char magic[FARBFELD_MAGIC_LEN];
> +    int ret;
> +
> +    if ((ret = avio_read(ctx->pb, magic, FARBFELD_MAGIC_LEN)) < 0)
> +        return ret;
> +
> +    if (memcmp(magic, "farbfeld", FARBFELD_MAGIC_LEN))
> +        return AVERROR_INVALIDDATA;
> +
> +    // width and height are assumed to be constant
> +    avio_skip(ctx->pb, 8);
> +
> +    if ((ret = av_get_packet(ctx->pb, pkt,
> +                                      ctx->packet_size -
> +                                      FARBFELD_HEADER_LEN)) < 0)
> +        return ret;
> +
> +    pkt->stream_index = 0;
> +
> +    return 0;
> +}
> +
> +#define OFFSET(x) offsetof(FarbfeldDemuxContext, x)
> +#define DEC AV_OPT_FLAG_DECODING_PARAM
> +
> +static const AVOption demuxoptions[] = {
> +    { "framerate", "set the video framerate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC },
> +    { NULL },
> +};
> +
> +static const AVClass farbfeld_demux_class = {
> +    .class_name = "FarbfeldDemuxContext",
> +    .item_name  = av_default_item_name,
> +    .option     = demuxoptions,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
> +const FFInputFormat ff_image_farbfeld_pipe_demuxer = {
> +    .p.name           = "farbfeld_pipe",
> +    .p.long_name      = NULL_IF_CONFIG_SMALL("piped farbfeld uncompressed image sequence"),
> +    .p.extensions     = "ff",
> +    .p.flags          = AVFMT_NOTIMESTAMPS,
> +    .p.priv_class     = &farbfeld_demux_class,
> +    .priv_data_size   = sizeof(FarbfeldDemuxContext),
> +    .read_header      = farbfeld_read_header,
> +    .read_packet      = farbfeld_read_packet,
> +};
> diff --git a/libavformat/farbfeldenc.c b/libavformat/farbfeldenc.c
> new file mode 100644
> index 0000000000..80baefb934
> --- /dev/null
> +++ b/libavformat/farbfeldenc.c
> @@ -0,0 +1,151 @@
> +/*
> + * misc image utilities
> + * YUV4MPEG muxer
> + * Image format
> + *
> + * Modified by Marcus B Spencer to suit the farbfeld muxer on 12 July 2024
> + *
> + * Copyright (c) 2001, 2002, 2003 Fabrice Bellard
> + * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
> + * Copyright (c) 2004 Michael Niedermayer
> + * Copyright (c) 2024 Marcus B Spencer
> + *
> + * 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
> + */
> +
> +#include "avformat.h"
> +#include "internal.h"
> +#include "libavutil/avstring.h"
> +#include "libavutil/frame.h"
> +#include "libavutil/opt.h"
> +#include "mux.h"
> +
> +typedef struct FarbfeldMuxContext {
> +    const AVClass *class;
> +    int start_number, img_number;
> +    int update;
> +} FarbfeldMuxContext;
> +
> +static int farbfeld_init(AVFormatContext *ctx)
> +{
> +    FarbfeldMuxContext *priv = ctx->priv_data;
> +
> +    if (ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_WRAPPED_AVFRAME &&
> +        ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_RAWVIDEO) {
> +        av_log(ctx, AV_LOG_ERROR, "Codec not supported.\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    if (ctx->streams[0]->codecpar->format != AV_PIX_FMT_RGBA64BE) {
> +        av_log(ctx, AV_LOG_ERROR,
> +            "farbfeld only supports the rgba64be pixel format. "
> +            "Add '-pix_fmt rgba64be' to your output options to resolve "
> +            "this error.\n"
> +        );
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    priv->img_number = priv->start_number;
> +
> +    return 0;
> +}
> +
> +static int farbfeld_write_packet(AVFormatContext *ctx, AVPacket *pkt)
> +{
> +    AVStream *st = ctx->streams[pkt->stream_index];
> +    int width = st->codecpar->width, height = st->codecpar->height;
> +    FarbfeldMuxContext *priv = ctx->priv_data;
> +    char filename[1024];
> +    const uint8_t *src;
> +    const AVFrame *p;
> +    AVIOContext *pb;
> +    int ret;
> +
> +    if (priv->update)
> +        av_strlcpy(filename, ctx->url, sizeof filename);
> +    else if (av_get_frame_filename2(filename, sizeof filename, ctx->url,
> +        priv->img_number, AV_FRAME_FILENAME_FLAGS_MULTIPLE) < 0) {
> +        if (priv->img_number == priv->start_number) {
> +            av_log(ctx, AV_LOG_WARNING, "The specified filename '%s' does not contain an image sequence pattern or a pattern is invalid.\n", ctx->url);
> +            av_log(ctx, AV_LOG_WARNING,
> +                   "Use a pattern such as %%03d for an image sequence or "
> +                   "use the -update option (with -frames:v 1 if needed) to write a single image.\n");
> +            av_strlcpy(filename, ctx->url, sizeof filename);
> +        } else {
> +            av_log(ctx, AV_LOG_ERROR, "Cannot write more than one file with the same name.\n");
> +            return AVERROR(EINVAL);
> +        }
> +    }

I'm not very happy with having code copied from img2enc.c. I'd prefer
if this was factored out and reused instead (we'd also get more
img2enc.c functionality for free this way).

But I know other developers don't mind copying small chunks of code
like this, and the refactoring could be done later, so I guess this is
ok for now.

[...]

Also it might be good to add a fate test.

Ramiro
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