[FFmpeg-devel,v9,2/5] avcodec/libjxl: add Jpeg XL decoding via libjxl

This commit adds decoding support to libavcodec
for Jpeg XL images via the external library libjxl.
---
 MAINTAINERS               |   1 +
 configure                 |   5 +
 doc/general_contents.texi |   7 +
 libavcodec/Makefile       |   1 +
 libavcodec/allcodecs.c    |   1 +
 libavcodec/libjxl.c       |  70 +++++++++
 libavcodec/libjxl.h       |  48 ++++++
 libavcodec/libjxldec.c    | 302 ++++++++++++++++++++++++++++++++++++++
 8 files changed, 435 insertions(+)
 create mode 100644 libavcodec/libjxl.c
 create mode 100644 libavcodec/libjxl.h
 create mode 100644 libavcodec/libjxldec.c

Leo Izen:
> This commit adds decoding support to libavcodec
> for Jpeg XL images via the external library libjxl.
> ---
>  MAINTAINERS               |   1 +
>  configure                 |   5 +
>  doc/general_contents.texi |   7 +
>  libavcodec/Makefile       |   1 +
>  libavcodec/allcodecs.c    |   1 +
>  libavcodec/libjxl.c       |  70 +++++++++
>  libavcodec/libjxl.h       |  48 ++++++
>  libavcodec/libjxldec.c    | 302 ++++++++++++++++++++++++++++++++++++++
>  8 files changed, 435 insertions(+)
>  create mode 100644 libavcodec/libjxl.c
>  create mode 100644 libavcodec/libjxl.h
>  create mode 100644 libavcodec/libjxldec.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2e0de9e224..875d25ca89 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -195,6 +195,7 @@ Codecs:
>    libcodec2.c                           Tomas Härdin
>    libdirac*                             David Conrad
>    libdavs2.c                            Huiwen Ren
> +  libjxl*.c, libjxl.h                   Leo Izen
>    libgsm.c                              Michel Bardiaux
>    libkvazaar.c                          Arttu Ylä-Outinen
>    libopenh264enc.c                      Martin Storsjo, Linjie Fu
> diff --git a/configure b/configure
> index a7953ffc16..4e28114d9c 100755
> --- a/configure
> +++ b/configure
> @@ -240,6 +240,7 @@ External library support:
>    --enable-libiec61883     enable iec61883 via libiec61883 [no]
>    --enable-libilbc         enable iLBC de/encoding via libilbc [no]
>    --enable-libjack         enable JACK audio sound server [no]
> +  --enable-libjxl          enable JPEG XL decoding via libjxl [no]
>    --enable-libklvanc       enable Kernel Labs VANC processing [no]
>    --enable-libkvazaar      enable HEVC encoding via libkvazaar [no]
>    --enable-liblensfun      enable lensfun lens correction [no]
> @@ -1833,6 +1834,7 @@ EXTERNAL_LIBRARY_LIST="
>      libiec61883
>      libilbc
>      libjack
> +    libjxl
>      libklvanc
>      libkvazaar
>      libmodplug
> @@ -3329,6 +3331,7 @@ libgsm_ms_decoder_deps="libgsm"
>  libgsm_ms_encoder_deps="libgsm"
>  libilbc_decoder_deps="libilbc"
>  libilbc_encoder_deps="libilbc"
> +libjxl_decoder_deps="libjxl libjxl_threads"
>  libkvazaar_encoder_deps="libkvazaar"
>  libmodplug_demuxer_deps="libmodplug"
>  libmp3lame_encoder_deps="libmp3lame"
> @@ -6541,6 +6544,8 @@ enabled libgsm            && { for gsm_hdr in "gsm.h" "gsm/gsm.h"; do
>                                     check_lib libgsm "${gsm_hdr}" gsm_create -lgsm && break;
>                                 done || die "ERROR: libgsm not found"; }
>  enabled libilbc           && require libilbc ilbc.h WebRtcIlbcfix_InitDecode -lilbc $pthreads_extralibs
> +enabled libjxl            && require_pkg_config libjxl "libjxl >= 0.7.0" jxl/decode.h JxlDecoderVersion &&
> +                             require_pkg_config libjxl_threads "libjxl_threads >= 0.7.0" jxl/thread_parallel_runner.h JxlThreadParallelRunner
>  enabled libklvanc         && require libklvanc libklvanc/vanc.h klvanc_context_create -lklvanc
>  enabled libkvazaar        && require_pkg_config libkvazaar "kvazaar >= 0.8.1" kvazaar.h kvz_api_get
>  enabled liblensfun        && require_pkg_config liblensfun lensfun lensfun.h lf_db_new
> diff --git a/doc/general_contents.texi b/doc/general_contents.texi
> index fcd9da1b34..a893347fbe 100644
> --- a/doc/general_contents.texi
> +++ b/doc/general_contents.texi
> @@ -171,6 +171,13 @@ Go to @url{https://github.com/TimothyGu/libilbc} and follow the instructions for
>  installing the library. Then pass @code{--enable-libilbc} to configure to
>  enable it.
>  
> +@section libjxl
> +
> +JPEG XL is an image format intended to fully replace legacy JPEG for an extended
> +period of life. See @url{https://jpegxl.info/} for more information, and see
> +@url{https://github.com/libjxl/libjxl} for the library source. You can pass
> +@code{--enable-libjxl} to configure in order enable the libjxl wrapper.
> +
>  @section libvpx
>  
>  FFmpeg can make use of the libvpx library for VP8/VP9 decoding and encoding.
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 3723601b3d..c00b0d3246 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -1060,6 +1060,7 @@ OBJS-$(CONFIG_LIBGSM_MS_DECODER)          += libgsmdec.o
>  OBJS-$(CONFIG_LIBGSM_MS_ENCODER)          += libgsmenc.o
>  OBJS-$(CONFIG_LIBILBC_DECODER)            += libilbc.o
>  OBJS-$(CONFIG_LIBILBC_ENCODER)            += libilbc.o
> +OBJS-$(CONFIG_LIBJXL_DECODER)             += libjxldec.o libjxl.o
>  OBJS-$(CONFIG_LIBKVAZAAR_ENCODER)         += libkvazaar.o
>  OBJS-$(CONFIG_LIBMP3LAME_ENCODER)         += libmp3lame.o
>  OBJS-$(CONFIG_LIBOPENCORE_AMRNB_DECODER)  += libopencore-amr.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index 22d56760ec..a9cd69dfce 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -749,6 +749,7 @@ extern const FFCodec ff_libgsm_ms_encoder;
>  extern const FFCodec ff_libgsm_ms_decoder;
>  extern const FFCodec ff_libilbc_encoder;
>  extern const FFCodec ff_libilbc_decoder;
> +extern const FFCodec ff_libjxl_decoder;
>  extern const FFCodec ff_libmp3lame_encoder;
>  extern const FFCodec ff_libopencore_amrnb_encoder;
>  extern const FFCodec ff_libopencore_amrnb_decoder;
> diff --git a/libavcodec/libjxl.c b/libavcodec/libjxl.c
> new file mode 100644
> index 0000000000..204d91d8a8
> --- /dev/null
> +++ b/libavcodec/libjxl.c
> @@ -0,0 +1,70 @@
> +/*
> + * JPEG XL de/encoding via libjxl, common support implementation
> + * Copyright (c) 2021 Leo Izen <leo.izen@gmail.com>
> + *
> + * 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
> + */
> +
> +/**
> + * @file
> + * JPEG XL via libjxl common support implementation
> + */
> +
> +#include "libavutil/cpu.h"
> +#include "libavutil/mem.h"
> +
> +#include <jxl/memory_manager.h>
> +#include "libjxl.h"
> +
> +size_t ff_libjxl_get_threadcount(int threads)
> +{
> +    if (threads <= 0)
> +        return av_cpu_count();
> +    if (threads == 1)
> +        return 0;
> +    return threads;
> +}
> +
> +/**
> + * Wrapper around av_malloc used as a jpegxl_alloc_func.
> + *
> + * @param  opaque opaque pointer for jpegxl_alloc_func, always ignored
> + * @param  size Size in bytes for the memory block to be allocated
> + * @return Pointer to the allocated block, or `NULL` if it cannot be allocated
> + */
> +static void *libjxl_av_malloc(void *opaque, size_t size)
> +{
> +    return av_malloc(size);
> +}
> +
> +/**
> + * Wrapper around av_free used as a jpegxl_free_func.
> + *
> + * @param opaque  opaque pointer for jpegxl_free_func, always ignored
> + * @param address Pointer to the allocated block, to free. `NULL` permitted as a no-op.
> + */
> +static void libjxl_av_free(void *opaque, void *address)
> +{
> +    av_free(address);
> +}
> +
> +void ff_libjxl_init_memory_manager(JxlMemoryManager *manager)
> +{
> +    manager->opaque = NULL;
> +    manager->alloc = &libjxl_av_malloc;
> +    manager->free = &libjxl_av_free;
> +}
> diff --git a/libavcodec/libjxl.h b/libavcodec/libjxl.h
> new file mode 100644
> index 0000000000..5387c438fd
> --- /dev/null
> +++ b/libavcodec/libjxl.h
> @@ -0,0 +1,48 @@
> +/*
> + * JPEG XL de/encoding via libjxl, common support header
> + * Copyright (c) 2021 Leo Izen <leo.izen@gmail.com>
> + *
> + * 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
> + */
> +
> +/**
> + * @file
> + * JPEG XL via libjxl common support header
> + */
> +
> +#ifndef AVCODEC_LIBJXL_H
> +#define AVCODEC_LIBJXL_H
> +
> +#include <jxl/memory_manager.h>
> +
> +/**
> + * Transform threadcount in ffmpeg to one used by libjxl.
> + *
> + * @param  threads ffmpeg's threads AVOption
> + * @return         thread count for libjxl's parallel runner
> + */
> +size_t ff_libjxl_get_threadcount(int threads);
> +
> +/**
> + * Initialize and populate a JxlMemoryManager
> + * with av_malloc() and av_free() so libjxl will use these
> + * functions.
> + * @param manager a pointer to a JxlMemoryManager struct
> + */
> +void ff_libjxl_init_memory_manager(JxlMemoryManager *manager);
> +
> +#endif /* AVCODEC_LIBJXL_H */
> diff --git a/libavcodec/libjxldec.c b/libavcodec/libjxldec.c
> new file mode 100644
> index 0000000000..ad22971fbb
> --- /dev/null
> +++ b/libavcodec/libjxldec.c
> @@ -0,0 +1,302 @@
> +/*
> + * JPEG XL decoding support via libjxl
> + * Copyright (c) 2021 Leo Izen <leo.izen@gmail.com>
> + *
> + * 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
> + */
> +
> +/**
> + * @file
> + * JPEG XL decoder using libjxl
> + */
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/common.h"
> +#include "libavutil/error.h"
> +#include "libavutil/mem.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/pixdesc.h"
> +#include "libavutil/pixfmt.h"
> +#include "libavutil/frame.h"
> +#include "libavutil/version.h"

What do you need version for? And opt.h?

> +
> +#include "avcodec.h"
> +#include "codec_internal.h"
> +#include "internal.h"
> +
> +#include <jxl/decode.h>
> +#include <jxl/thread_parallel_runner.h>
> +#include "libjxl.h"
> +
> +typedef struct LibJxlDecodeContext {
> +    void *runner;
> +    JxlDecoder *decoder;
> +    JxlBasicInfo basic_info;
> +    JxlPixelFormat jxl_pixfmt;
> +    JxlDecoderStatus events;
> +    uint8_t *iccp;
> +    size_t iccp_len;
> +} LibJxlDecodeContext;
> +
> +static int libjxl_init_jxl_decoder(AVCodecContext *avctx)
> +{
> +    LibJxlDecodeContext *ctx = avctx->priv_data;
> +
> +    ctx->events = JXL_DEC_BASIC_INFO | JXL_DEC_FULL_IMAGE | JXL_DEC_FRAME | JXL_DEC_COLOR_ENCODING;
> +    if (JxlDecoderSubscribeEvents(ctx->decoder, ctx->events) != JXL_DEC_SUCCESS) {
> +        av_log(avctx, AV_LOG_ERROR, "Error subscribing to JXL events\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    if (JxlDecoderSetParallelRunner(ctx->decoder, JxlThreadParallelRunner, ctx->runner) != JXL_DEC_SUCCESS) {
> +        av_log(avctx, AV_LOG_ERROR, "Failed to set JxlThreadParallelRunner\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    memset(&ctx->basic_info, 0, sizeof(JxlBasicInfo));
> +    memset(&ctx->jxl_pixfmt, 0, sizeof(JxlPixelFormat));
> +    return 0;
> +}
> +
> +static av_cold int libjxl_decode_init(AVCodecContext *avctx)
> +{
> +    LibJxlDecodeContext *ctx = avctx->priv_data;
> +    JxlMemoryManager manager;
> +
> +    ff_libjxl_init_memory_manager(&manager);
> +    ctx->decoder = JxlDecoderCreate(&manager);
> +    if (!ctx->decoder) {
> +        av_log(avctx, AV_LOG_ERROR, "Failed to create JxlDecoder\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    ctx->runner = JxlThreadParallelRunnerCreate(&manager, ff_libjxl_get_threadcount(avctx->thread_count));
> +    if (!ctx->runner) {
> +        av_log(avctx, AV_LOG_ERROR, "Failed to create JxlThreadParallelRunner\n");
> +        return AVERROR_EXTERNAL;
> +    }
> +
> +    return libjxl_init_jxl_decoder(avctx);
> +}
> +
> +static enum AVPixelFormat libjxl_get_pix_fmt(AVCodecContext *avctx, JxlBasicInfo *basic_info, JxlPixelFormat *format)
> +{
> +    format->endianness = JXL_NATIVE_ENDIAN;
> +    format->num_channels = basic_info->num_color_channels + (basic_info->alpha_bits > 0);
> +    /* av_malloc handles alignment already */
> +    format->align = 1;
> +    /* Gray */
> +    if (basic_info->num_color_channels == 1) {
> +        if (basic_info->bits_per_sample <= 8) {
> +            format->data_type = JXL_TYPE_UINT8;
> +            return basic_info->alpha_bits ? AV_PIX_FMT_YA8 : AV_PIX_FMT_GRAY8;
> +        }
> +        if (basic_info->exponent_bits_per_sample || basic_info->bits_per_sample > 16) {
> +            if (basic_info->alpha_bits)
> +                return AV_PIX_FMT_NONE;
> +            format->data_type = JXL_TYPE_FLOAT;
> +            return AV_PIX_FMT_GRAYF32;
> +        }
> +        format->data_type = JXL_TYPE_UINT16;
> +        return basic_info->alpha_bits ? AV_PIX_FMT_YA16 : AV_PIX_FMT_GRAY16;
> +    }
> +    /* rgb only */
> +    /* libjxl only supports packed RGB and gray output at the moment */
> +    if (basic_info->num_color_channels == 3) {
> +        if (basic_info->bits_per_sample <= 8) {
> +            format->data_type = JXL_TYPE_UINT8;
> +            return basic_info->alpha_bits ? AV_PIX_FMT_RGBA : AV_PIX_FMT_RGB24;
> +        }
> +        if (basic_info->bits_per_sample > 16)
> +            av_log(avctx, AV_LOG_WARNING, "Downsampling larger integer to 16-bit via libjxl\n");
> +        if (basic_info->exponent_bits_per_sample)
> +            av_log(avctx, AV_LOG_WARNING, "Downsampling float to 16-bit integer via libjxl\n");
> +        format->data_type = JXL_TYPE_UINT16;
> +        return basic_info->alpha_bits ? AV_PIX_FMT_RGBA64 : AV_PIX_FMT_RGB48;
> +    }
> +    return AV_PIX_FMT_NONE;
> +}
> +
> +static void libjxl_row_fill(void *avframe, size_t x, size_t y, size_t num_pixels, const void *pixels)
> +{
> +    AVFrame *frame = avframe;
> +    int bytes = av_get_padded_bits_per_pixel(av_pix_fmt_desc_get(frame->format)) / 8;
> +    size_t offset = y * frame->linesize[0] + x * bytes;
> +    memcpy(frame->data[0] + offset, pixels, num_pixels * bytes);
> +}
> +
> +static int libjxl_decode_frame(AVCodecContext *avctx, void *avframe, int *got_frame, AVPacket *avpkt)
> +{
> +    LibJxlDecodeContext *ctx = avctx->priv_data;
> +    uint8_t *buf = avpkt->data;
> +    size_t remaining = avpkt->size;
> +    AVFrame *frame = avframe;
> +    JxlDecoderStatus status;
> +    int ff_status;

The typical name for this variable would be ret; JxlDecoderStatus could
be could jret.

> +    *got_frame = 0;
> +
> +    while (1) {
> +        /*
> +         * it only returns JXL_DEC_ERROR here if the input
> +         * was not released since the last time this was called
> +         * if this happens, it's a programmer error

Is it guaranteed that this will never happen, e.g. when ff_get_buffer()
or anything else fails?

> +         */
> +        status = JxlDecoderSetInput(ctx->decoder, buf, remaining);
> +        av_assert0(status != JXL_DEC_ERROR);
> +
> +        status = JxlDecoderProcessInput(ctx->decoder);
> +        /*
> +         * JxlDecoderReleaseInput returns the number
> +         * of bytes remaining to be read, rather than
> +         * the number of bytes that it did read
> +         */
> +        remaining = JxlDecoderReleaseInput(ctx->decoder);
> +        buf = avpkt->data + avpkt->size - remaining;
> +
> +        switch(status) {
> +        case JXL_DEC_ERROR:
> +            av_log(avctx, AV_LOG_ERROR, "Unknown libjxl decode error\n");
> +            return AVERROR_EXTERNAL;
> +        case JXL_DEC_NEED_MORE_INPUT:
> +            if (remaining == 0) {
> +                av_log(avctx, AV_LOG_WARNING, "Unexpected end of JXL codestream\n");
> +                return AVERROR(EAGAIN);
> +            }
> +            av_log(avctx, AV_LOG_DEBUG, "NEED_MORE_INPUT event emitted\n");
> +            continue;
> +        case JXL_DEC_BASIC_INFO:
> +            av_log(avctx, AV_LOG_DEBUG, "BASIC_INFO event emitted\n");
> +            if (JxlDecoderGetBasicInfo(ctx->decoder, &ctx->basic_info) != JXL_DEC_SUCCESS) {
> +                /*
> +                 * this should never happen
> +                 * if it does it is likely a libjxl decoder bug
> +                 */
> +                av_log(avctx, AV_LOG_ERROR, "Bad libjxl basic info event\n");
> +                return AVERROR_EXTERNAL;
> +            }
> +            avctx->pix_fmt = libjxl_get_pix_fmt(avctx, &ctx->basic_info, &ctx->jxl_pixfmt);
> +            if (avctx->pix_fmt == AV_PIX_FMT_NONE) {
> +                av_log(avctx, AV_LOG_ERROR, "Bad libjxl pixel format\n");
> +                return AVERROR_EXTERNAL;
> +            }
> +            ff_status = ff_set_dimensions(avctx, ctx->basic_info.xsize, ctx->basic_info.ysize);
> +            if (ff_status < 0)
> +                return ff_status;
> +            /*
> +             * We rewind the decoder and ask for everything again
> +             * This futureproofs the decoder since it will make
> +             * adding a parser or a dedicated demuxer much easier
> +             */
> +            buf = avpkt->data;
> +            remaining = avpkt->size;
> +            JxlDecoderRewind(ctx->decoder);
> +            ctx->events &= ~JXL_DEC_BASIC_INFO;
> +            if (JxlDecoderSubscribeEvents(ctx->decoder, ctx->events) != JXL_DEC_SUCCESS) {
> +                av_log(avctx, AV_LOG_ERROR, "Error subscribing to JXL events after rewind\n");
> +                return AVERROR_EXTERNAL;
> +            }
> +            continue;
> +        case JXL_DEC_COLOR_ENCODING:
> +            av_log(avctx, AV_LOG_DEBUG, "COLOR_ENCODING event emitted\n");
> +            status = JxlDecoderGetICCProfileSize(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_ORIGINAL, &ctx->iccp_len);
> +            if (status == JXL_DEC_SUCCESS && ctx->iccp_len > 0) {
> +                if (ctx->iccp)
> +                    av_freep(&ctx->iccp);
> +                ctx->iccp = av_malloc(ctx->iccp_len);

Use av_buffer_alloc() here, as this will allow to avoid the memcpy when
attaching the profile to the frame.

> +                if (!ctx->iccp)
> +                    return AVERROR(ENOMEM);
> +                status = JxlDecoderGetColorAsICCProfile(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_ORIGINAL, ctx->iccp, ctx->iccp_len);
> +                if (status != JXL_DEC_SUCCESS)
> +                    av_freep(&ctx->iccp);
> +            }
> +            continue;
> +        case JXL_DEC_FRAME:
> +        case JXL_DEC_NEED_IMAGE_OUT_BUFFER:
> +            /*
> +             * We don't do this at basic info time
> +             * because it will happen again when we
> +             * rewind anyway
> +             */
> +            av_log(avctx, AV_LOG_DEBUG, "%s event emitted\n", status == JXL_DEC_FRAME ? "FRAME" : "NEED_IMAGE_OUT_BUFFER");
> +            ff_status = ff_get_buffer(avctx, frame, 0);
> +            if (ff_status < 0)
> +                return ff_status;
> +            if (JxlDecoderSetImageOutCallback(ctx->decoder, &ctx->jxl_pixfmt, &libjxl_row_fill, frame) != JXL_DEC_SUCCESS) {
> +                av_log(avctx, AV_LOG_ERROR, "Bad libjxl dec need image out buffer event\n");
> +                return AVERROR_EXTERNAL;
> +            }
> +            continue;
> +        case JXL_DEC_FULL_IMAGE:
> +            /* full image is one frame, even if animated */
> +            av_log(avctx, AV_LOG_DEBUG, "FULL_IMAGE event emitted\n");
> +            *got_frame = 1;
> +            frame->pict_type = AV_PICTURE_TYPE_I;
> +            frame->key_frame = 1;
> +            if (ctx->iccp) {
> +                AVFrameSideData *sd = av_frame_new_side_data(frame, AV_FRAME_DATA_ICC_PROFILE, ctx->iccp_len);
> +                if (!sd)
> +                    return AVERROR(ENOMEM);
> +                memcpy(sd->data, ctx->iccp, ctx->iccp_len);
> +                av_dict_set(&sd->metadata, "name", "", 0);

The name is optional; so don't set this.

> +            }
> +            return avpkt->size - remaining;
> +        case JXL_DEC_SUCCESS:
> +            av_log(avctx, AV_LOG_DEBUG, "SUCCESS event emitted\n");
> +            /*
> +             * The file has finished decoding
> +             * reset the decoder to let us
> +             * reuse it again for the next image
> +             */
> +            JxlDecoderReset(ctx->decoder);
> +            libjxl_init_jxl_decoder(avctx);
> +            buf = avpkt->data;
> +            remaining = avpkt->size;
> +            continue;
> +        default:
> +             av_log(avctx, AV_LOG_ERROR, "Bad libjxl event: %d\n", status);
> +             return AVERROR_EXTERNAL;
> +        }
> +    }
> +}
> +
> +static av_cold int libjxl_decode_close(AVCodecContext *avctx)
> +{
> +    LibJxlDecodeContext *ctx = avctx->priv_data;
> +    if (ctx->runner)
> +        JxlThreadParallelRunnerDestroy(ctx->runner);
> +    ctx->runner = NULL;
> +    if (ctx->decoder)
> +        JxlDecoderDestroy(ctx->decoder);
> +    ctx->decoder = NULL;
> +    if (ctx->iccp)

Unnecessary check

> +        av_freep(&ctx->iccp);
> +    return 0;
> +}
> +
> +const FFCodec ff_libjxl_decoder = {
> +    .p.name           = "libjxl",
> +    .p.long_name      = NULL_IF_CONFIG_SMALL("libjxl JPEG XL"),
> +    .p.type           = AVMEDIA_TYPE_VIDEO,
> +    .p.id             = AV_CODEC_ID_JPEGXL,
> +    .priv_data_size   = sizeof(LibJxlDecodeContext),
> +    .init             = libjxl_decode_init,
> +    .decode           = libjxl_decode_frame,
> +    .close            = libjxl_decode_close,
> +    .p.capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_OTHER_THREADS,
> +    .caps_internal    = FF_CODEC_CAP_AUTO_THREADS | FF_CODEC_CAP_INIT_CLEANUP,
> +    .p.wrapper_name   = "libjxl",
> +};