[FFmpeg-devel] [PATCH] Add FITS Decoder

Nicolas George george at nsup.org
Fri Jun 30 16:08:17 EEST 2017


Hi. A few technical / cosmetic remarks below. I do not know the FITS
format itself more than in passing.

Le duodi 12 messidor, an CCXXV, Paras Chadha a écrit :
> Made the changes suggested above
> 
> Signed-off-by: Paras Chadha <paraschadha18 at gmail.com>
> ---
>  Changelog               |   1 +
>  doc/general.texi        |   2 +
>  libavcodec/Makefile     |   1 +
>  libavcodec/allcodecs.c  |   1 +
>  libavcodec/avcodec.h    |   1 +
>  libavcodec/codec_desc.c |   8 +
>  libavcodec/fitsdec.c    | 580 ++++++++++++++++++++++++++++++++++++++++++++++++
>  libavcodec/version.h    |   4 +-
>  libavformat/img2.c      |   1 +
>  9 files changed, 597 insertions(+), 2 deletions(-)
>  create mode 100644 libavcodec/fitsdec.c
> 
> diff --git a/Changelog b/Changelog
> index a8726c6..2c2bdec 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -26,6 +26,7 @@ version <next>:
>    --x86asmexe=yasm to configure to restore the old behavior.
>  - additional frame format support for Interplay MVE movies
>  - support for decoding through D3D11VA in ffmpeg
> +- FITS demuxer and decoder
> 
>  version 3.3:
>  - CrystalHD decoder moved to new decode API
> diff --git a/doc/general.texi b/doc/general.texi
> index 8f582d5..c00ce32 100644
> --- a/doc/general.texi
> +++ b/doc/general.texi
> @@ -591,6 +591,8 @@ following image formats are supported:
>      @tab Digital Picture Exchange
>  @item EXR          @tab   @tab X
>      @tab OpenEXR
> + at item FITS         @tab   @tab X
> +    @tab Flexible Image Transport System
>  @item JPEG         @tab X @tab X
>      @tab Progressive JPEG is not supported.
>  @item JPEG 2000    @tab X @tab X
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index b440a00..729e95e 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -291,6 +291,7 @@ OBJS-$(CONFIG_FFV1_DECODER)            += ffv1dec.o ffv1.o
>  OBJS-$(CONFIG_FFV1_ENCODER)            += ffv1enc.o ffv1.o
>  OBJS-$(CONFIG_FFWAVESYNTH_DECODER)     += ffwavesynth.o
>  OBJS-$(CONFIG_FIC_DECODER)             += fic.o
> +OBJS-$(CONFIG_FITS_DECODER)            += fitsdec.o
>  OBJS-$(CONFIG_FLAC_DECODER)            += flacdec.o flacdata.o flac.o
>  OBJS-$(CONFIG_FLAC_ENCODER)            += flacenc.o flacdata.o flac.o vorbis_data.o
>  OBJS-$(CONFIG_FLASHSV_DECODER)         += flashsv.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index 0243f47..a4cfd80 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -192,6 +192,7 @@ static void register_all(void)
>      REGISTER_ENCDEC (FFV1,              ffv1);
>      REGISTER_ENCDEC (FFVHUFF,           ffvhuff);
>      REGISTER_DECODER(FIC,               fic);
> +    REGISTER_DECODER(FITS,              fits);
>      REGISTER_ENCDEC (FLASHSV,           flashsv);
>      REGISTER_ENCDEC (FLASHSV2,          flashsv2);
>      REGISTER_DECODER(FLIC,              flic);
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index b697afa..8eba460 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -447,6 +447,7 @@ enum AVCodecID {
>      AV_CODEC_ID_SRGC,
>      AV_CODEC_ID_SVG,
>      AV_CODEC_ID_GDV,
> +    AV_CODEC_ID_FITS,
> 
>      /* various PCM "codecs" */
>      AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> index cf1246e..0112517 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -1464,6 +1464,14 @@ static const AVCodecDescriptor codec_descriptors[] = {
>                       AV_CODEC_PROP_LOSSLESS,
>      },
>      {
> +        .id        = AV_CODEC_ID_FITS,
> +        .type      = AVMEDIA_TYPE_VIDEO,
> +        .name      = "fits",
> +        .long_name = NULL_IF_CONFIG_SMALL("Flexible Image Transport System"),
> +        .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSY |
> +                     AV_CODEC_PROP_LOSSLESS,
> +    },
> +    {
>          .id        = AV_CODEC_ID_GIF,
>          .type      = AVMEDIA_TYPE_VIDEO,
>          .name      = "gif",
> diff --git a/libavcodec/fitsdec.c b/libavcodec/fitsdec.c
> new file mode 100644
> index 0000000..4eaf3c8
> --- /dev/null
> +++ b/libavcodec/fitsdec.c
> @@ -0,0 +1,580 @@
> +/*
> + * FITS image decoder
> + * Copyright (c) 2017 Paras Chadha
> + *
> + * 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
> + * FITS image decoder
> + * It supports all 2-d images alongwith, bzero, bscale and blank keywords.
> + * RGBA images are supported as NAXIS3 = 3 or 4 i.e. Planes in RGBA order. Also CTYPE = 'RGB ' should be present.
> + * Also to interpret data, values are linearly scaled using min-max scaling but not RGB images.

Please add a link to the specification you followed.

> + */
> +
> +#include "avcodec.h"
> +#include "internal.h"
> +#include <float.h>
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/intfloat.h"
> +#include "libavutil/dict.h"
> +
> +/**
> + * Structure to store the header keywords in FITS file
> + */
> +typedef struct FITSContext {

> +    char simple;

This field is only used in fits_read_header(), it should be a local
variable.

> +    int bitpix;
> +    int64_t blank;

> +    int naxis;

Ditto.

> +    int naxisn[3];
> +    int rgb; /**< 1 if file contains RGB image, 0 otherwise */

> +    int xtension;

Ditto.

> +    double bscale;
> +    double bzero;
> +    double data_min;
> +    double data_max;
> +} FITSDecContext;

In fact, I believe not a single of these fields has a value that
survives the decode_frame() call: it the whole header structure should
be a local variable in decode_frame().

> +
> +/**

> + * function calculates the data_min and data_max values from the data.

The style for doxygen comments is impersonal verbs: "Calculate the ...".

> + * This is called if the values are not present in the header.

> + * @param ptr8 - pointer to the data
> + * @param header - pointer to the header
> + * @return 1, if calculated successfully, otherwise AVERROR_INVALIDDATA

Please drop the dashes and comma. The last two comments apply for all
doxygen comments.

And 0 is usually used for success.

> + */
> +static int fill_data_min_max(const uint8_t * ptr8, FITSDecContext * header, const uint8_t * end)
> +{
> +    int16_t t16;
> +    int32_t t32;
> +    int64_t t64;
> +    float tflt;
> +    double tdbl;
> +    int i, j;
> +
> +    header->data_min = DBL_MAX;
> +    header->data_max = DBL_MIN;
> +    switch (header->bitpix) {
> +        case -64:

> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    tdbl = av_int2double(AV_RB64(ptr8));
> +                    if (tdbl > header->data_max)
> +                        header->data_max = tdbl;
> +                    if (tdbl < header->data_min)
> +                        header->data_min = tdbl;
> +                    ptr8 += 8;
> +                }
> +            }
> +            break;
> +        case -32:
> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    tflt = av_int2float(AV_RB32(ptr8));
> +                    if (tflt > header->data_max)
> +                        header->data_max = tflt;
> +                    if (tflt < header->data_min)
> +                        header->data_min = tflt;
> +                    ptr8 += 4;
> +                }
> +            }
> +            break;
> +        case 8:
> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    if (ptr8[0] != header->blank) {
> +                        if (ptr8[0] > header->data_max)
> +                            header->data_max = ptr8[0];
> +                        if (ptr8[0] < header->data_min)
> +                            header->data_min = ptr8[0];
> +                    }
> +                    ptr8++;
> +                }
> +            }
> +            break;
> +        case 16:
> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    t16 = AV_RB16(ptr8);
> +                    if (t16 != header->blank) {
> +                        if (t16 > header->data_max)
> +                            header->data_max = t16;
> +                        if (t16 < header->data_min)
> +                            header->data_min = t16;
> +                    }
> +                    ptr8 += 2;
> +                }
> +            }
> +            break;
> +        case 32:
> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    t32 = AV_RB32(ptr8);
> +                    if (t32 != header->blank) {
> +                        if (t32 > header->data_max)
> +                            header->data_max = t32;
> +                        if (t32 < header->data_min)
> +                            header->data_min = t32;
> +                    }
> +                    ptr8 += 4;
> +                }
> +            }
> +            break;
> +        case 64:
> +            for (i = 0; i < header->naxisn[1]; i++) {
> +                for (j = 0; j < header->naxisn[0]; j++) {
> +                    t64 = AV_RB64(ptr8);
> +                    if (t64 != header->blank) {
> +                        if (t64 > header->data_max)
> +                            header->data_max = t64;
> +                        if (t64 < header->data_min)
> +                            header->data_min = t64;
> +                    }
> +                    ptr8 += 8;
> +                }
> +            }
> +            break;

Please find a way of factoring these almost-identical loops. A macro
would be the obvious choice.

> +        default:
> +            return AVERROR_INVALIDDATA;
> +    }
> +    return 1;
> +}
> +
> +/**
> + * function reads the fits header and stores the values in FITSDecContext pointed by header
> + * @param avctx - AVCodec context
> + * @param ptr - pointer to pointer to the data
> + * @param header - pointer to the FITSDecContext
> + * @param end - pointer to end of packet
> + * @return 1, if calculated successfully, otherwise AVERROR_INVALIDDATA
> + */
> +static int fits_read_header(AVCodecContext *avctx, const uint8_t **ptr, FITSDecContext * header,
> +                            const uint8_t * end, AVDictionary **meta)
> +{
> +    const uint8_t *ptr8 = *ptr;
> +    int lines_read = 0, i, dim_no, t, data_min_found = 0, data_max_found = 0, ret;
> +    uint64_t size=1;
> +    double d;
> +    AVDictionary *metadata = NULL;
> +    char keyword[10], value[72];
> +

> +    header->blank = LLONG_MIN;

This is almost certainly not the value you want.

> +    header->bscale = 1.0;
> +    header->bzero = 0;
> +    header->rgb = 0;
> +

> +    if (end - ptr8 < 80)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (sscanf(ptr8, "SIMPLE = %c", &header->simple) == 1) {

You did not check that there is a NUL character. A crafted input could
cause an over-read, and relying on the padding is bad style. I suggest
you check that there is at least one padding space at the end (and make
sure the sscanf patterns do not). As a macro or a small helper function,
for example.

Another possibility, more strictly conforming to the standard, would be
to copy the line into a 81-sized buffer.

> +        if (header->simple == 'F') {
> +            av_log(avctx, AV_LOG_WARNING, "not a standard FITS file\n");
> +            av_dict_set(&metadata, "SIMPLE", "F", 0);

> +        } else if (header->simple != 'T') {
> +            av_log(avctx, AV_LOG_ERROR, "invalid SIMPLE value, SIMPLE = %c\n", header->simple);
> +            return AVERROR_INVALIDDATA;
> +        } else {
> +            av_dict_set(&metadata, "SIMPLE", "T", 0);
> +        }

I strongly suggest to swap the if and else clause.

> +        header->xtension = 0;
> +    } else if (!strncmp(ptr8, "XTENSION= 'IMAGE", 16)) {
> +        header->xtension = 1;
> +        av_dict_set(&metadata, "XTENSION", "'IMAGE   '", 0);
> +    } else {
> +        av_log(avctx, AV_LOG_ERROR, "missing SIMPLE keyword or invalid XTENSION\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    ptr8 += 80;
> +    lines_read++;
> +
> +    if (end - ptr8 < 80)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (sscanf(ptr8, "BITPIX = %d", &header->bitpix) != 1) {
> +        av_log(avctx, AV_LOG_ERROR, "missing BITPIX keyword\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    av_dict_set_int(&metadata, "BITPIX", header->bitpix, 0);
> +    size = abs(header->bitpix) >> 3;
> +    ptr8 += 80;
> +    lines_read++;
> +
> +    if (end - ptr8 < 80)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (sscanf(ptr8, "NAXIS = %d", &header->naxis) != 1) {
> +        av_log(avctx, AV_LOG_ERROR, "missing NAXIS keyword\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    if (!header->naxis) {
> +        av_log(avctx, AV_LOG_ERROR, "No image data found, NAXIS = %d\n", header->naxis);
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    if (header->naxis != 2 && header->naxis != 3) {
> +        av_log(avctx, AV_LOG_ERROR, "unsupported number of dimensions, NAXIS = %d\n", header->naxis);
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    av_dict_set_int(&metadata, "NAXIS", header->naxis, 0);
> +    ptr8 += 80;
> +    lines_read++;
> +
> +    for (i = 0; i < header->naxis; i++) {
> +        if (end - ptr8 < 80)
> +            return AVERROR_INVALIDDATA;
> +
> +        if (sscanf(ptr8, "NAXIS%d = %d", &dim_no, &header->naxisn[i]) != 2 || dim_no != i+1) {
> +            av_log(avctx, AV_LOG_ERROR, "missing NAXIS%d keyword\n", i+1);
> +            return AVERROR_INVALIDDATA;
> +        }
> +

> +        ret = snprintf(keyword, 10, "NAXIS%d", dim_no);
> +        if (ret < 0 || ret >= 10) {

Use sizeof(keyword).

> +            return AVERROR_INVALIDDATA;
> +        }
> +
> +        av_dict_set_int(&metadata, keyword, header->naxisn[i], 0);

> +        size *= header->naxisn[i];

This can overflow.

> +        ptr8 += 80;
> +        lines_read++;
> +    }
> +

> +    if (end - ptr8 < 80)
> +            return AVERROR_INVALIDDATA;

Strange indentation.

> +
> +    while (strncmp(ptr8, "END", 3)) {
> +        if (sscanf(ptr8, "BLANK = %d", &t) == 1) {
> +            header->blank = t;
> +        } else if (sscanf(ptr8, "BSCALE = %lf", &d) == 1) {
> +            header->bscale = d;
> +        } else if (sscanf(ptr8, "BZERO = %lf", &d) == 1) {
> +            header->bzero = d;
> +        } else if (sscanf(ptr8, "DATAMAX = %lf", &d) == 1) {
> +            data_max_found = 1;
> +            header->data_max = d;
> +        } else if (sscanf(ptr8, "DATAMIN = %lf", &d) == 1) {
> +            data_min_found = 1;
> +            header->data_min = d;
> +        } else if (!strncmp(ptr8, "CTYPE3  = 'RGB", 14)) {
> +            header->rgb = 1;
> +            if (header->naxis != 3 || (header->naxisn[2] != 3 && header->naxisn[2] != 4)) {
> +                av_log(avctx, AV_LOG_ERROR, "File contains RGB image but NAXIS = %d and NAXIS3 = %d\n", header->naxis, header->naxisn[2]);
> +                return AVERROR_INVALIDDATA;
> +            }
> +        }
> +
> +        if (ptr8[8] == '=') {
> +            for (i = 0; i < 8 && ptr8[i] != ' '; i++) {
> +                keyword[i] = ptr8[i];
> +            }
> +            keyword[i] = '\0';
> +
> +            t = 0;
> +            i = 10;
> +            while (i < 80 && ptr8[i] == ' ')
> +                i++;
> +
> +            if (i < 80) {
> +                value[t] = ptr8[i];
> +                i++;
> +                t++;
> +                if (ptr8[i-1] == '\'') {
> +                    while (i < 80 && ptr8[i] != '\'') {
> +                        value[t] = ptr8[i];
> +                        i++;
> +                        t++;
> +                    }
> +                    value[t] = '\'';
> +                    t++;
> +                } else if (ptr8[i-1] == '(') {
> +                    while (i < 80 && ptr8[i] != ')') {
> +                        value[t] = ptr8[i];
> +                        i++;
> +                        t++;
> +                    }
> +                    value[t] = ')';
> +                    t++;
> +                } else {
> +                    while (i < 80 && ptr8[i] != ' ' && ptr8[i] != '/') {
> +                        value[t] = ptr8[i];
> +                        i++;
> +                        t++;
> +                    }
> +                }
> +            }
> +
> +            value[t] = '\0';
> +            av_dict_set(&metadata, keyword, value, 0);
> +        }
> +
> +        ptr8 += 80;
> +        lines_read++;
> +
> +        if (end - ptr8 < 80)
> +            return AVERROR_INVALIDDATA;
> +    }
> +
> +    if (!header->rgb && header->naxis != 2){
> +        av_log(avctx, AV_LOG_ERROR, "unsupported number of dimensions, NAXIS = %d\n", header->naxis);
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    ptr8 += 80;
> +    lines_read++;
> +    lines_read %= 36;
> +
> +    t = ((36 - lines_read) % 36) * 80;
> +    if (end - ptr8 < t)
> +        return AVERROR_INVALIDDATA;
> +    ptr8 += t;
> +    *ptr = ptr8;
> +
> +    if (end - ptr8 < size)
> +        return AVERROR_INVALIDDATA;
> +

> +    if (!header->rgb && (!data_min_found || !data_max_found)) {
> +        if ((ret = fill_data_min_max(ptr8, header, end)) < 0) {

If only one of the min/max is provided in the file, fill_data_min_max()
will be called and override both. It is on purpose?

> +            av_log(avctx, AV_LOG_ERROR, "invalid BITPIX, %d\n", header->bitpix);

> +            return AVERROR_INVALIDDATA;

return ret;

> +        }
> +    } else {
> +        /*
> +         * instead of applying bscale and bzero to every element, we can do inverse transformation on data_min and
> +         * data_max
> +         */
> +        header->data_min = (header->data_min - header->bzero) / header->bscale;
> +        header->data_max = (header->data_max - header->bzero) / header->bscale;
> +    }
> +
> +    *meta = metadata;
> +    return 1;
> +}
> +
> +static int fits_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
> +{
> +    AVFrame *p=data;
> +    const uint8_t *ptr8 = avpkt->data, *end;
> +    int16_t t16;
> +    int32_t t32;
> +    int64_t t64;
> +    float   tflt;
> +    double  tdbl;
> +    int ret, i, j;
> +    uint8_t *dst8;
> +    uint16_t *dst16;
> +    uint32_t *dst32;
> +    uint64_t *dst64, size, r, g, b, a, t;
> +    FITSDecContext * header = avctx->priv_data;
> +
> +    end = ptr8 + avpkt->size;
> +    if ((ret = fits_read_header(avctx, &ptr8, header, end, &p->metadata)) < 0)
> +        return ret;
> +
> +    size = (header->naxisn[0]) * (header->naxisn[1]);
> +
> +    if (header->rgb) {
> +        if (header->bitpix == 8) {
> +            avctx->pix_fmt = AV_PIX_FMT_RGB32;
> +        } else if (header->bitpix == 16) {
> +            avctx->pix_fmt = AV_PIX_FMT_RGBA64;
> +        } else {
> +            av_log(avctx, AV_LOG_ERROR, "unsupported BITPIX = %d\n", header->bitpix);
> +            return AVERROR_INVALIDDATA;
> +        }
> +    } else {
> +        if (header->bitpix == 8) {
> +            avctx->pix_fmt = AV_PIX_FMT_GRAY8;
> +        } else {
> +            avctx->pix_fmt = AV_PIX_FMT_GRAY16;
> +        }
> +    }
> +
> +    if ((ret = ff_set_dimensions(avctx, header->naxisn[0], header->naxisn[1])) < 0)
> +        return ret;
> +
> +    if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
> +        return ret;
> +
> +    if (header->rgb) {

> +        if (header->bitpix == 8) {
> +            for (i = 0; i < avctx->height; i++) {
> +                /*
> +                 * FITS stores images with bottom row first. Therefore we have
> +                 * to fill the image from bottom to top.
> +                 */
> +                dst32 = (uint32_t *)(p->data[0] + (avctx->height-i-1)* p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    if (header->naxisn[2] == 4) {
> +                        if (ptr8[size * 3] != header->blank)
> +                            t = ptr8[size * 3] * header->bscale + header->bzero;
> +                        a = t << 24;
> +                    } else {
> +                        a = (255 << 24);
> +                    }
> +
> +                    if (ptr8[0] != header->blank)
> +                        t = ptr8[0] * header->bscale + header->bzero;
> +                    r = t << 16;
> +
> +                    if (ptr8[size] != header->blank)
> +                        t = ptr8[size] * header->bscale + header->bzero;
> +                    g = t << 8;
> +
> +                    if (ptr8[size * 2] != header->blank)
> +                        t = ptr8[size * 2] * header->bscale + header->bzero;
> +                    b = t;
> +
> +                    *dst32++ = ((uint32_t)a) | ((uint32_t)r) | ((uint32_t)g) | ((uint32_t)b);
> +                    ptr8++;
> +                }
> +            }
> +        } else if (header->bitpix == 16) {
> +            // not tested ....
> +            for (i = 0; i < avctx->height; i++) {
> +                dst64 = (uint64_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +
> +                    if (header->naxisn[2] == 4) {
> +                        t = ((ptr8[size * 3] << 8) | ptr8[size * 3 + 1]);
> +                        if (t != header->blank)
> +                            t = t*header->bscale + header->bzero;
> +                        a = t << 48;
> +                    } else {
> +                        a = 65535ULL << 48;
> +                    }
> +
> +                    t = ptr8[0] << 8 | ptr8[1];
> +                    if (t != header->blank)
> +                        t = t*header->bscale + header->bzero;
> +                    r = t << 32;
> +
> +                    t = ptr8[size] << 8 | ptr8[size + 1];
> +                    if (t != header->blank)
> +                        t = t*header->bscale + header->bzero;
> +                    g = t << 16;
> +
> +                    t = ptr8[size * 2] << 8 | ptr8[size * 2 + 1];
> +                    if (t != header->blank)
> +                        t = t*header->bscale + header->bzero;
> +                    b = t;
> +
> +                    *dst64++ = a | r | g | b;
> +                    ptr8 += 2;
> +                }
> +            }
> +        }

These two almost identical blocks need to be factored.

> +    } else {
> +        if (header->bitpix == 8) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst8 = (uint8_t *) (p->data[0] + (avctx->height-i-1)* p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    if (ptr8[0] != header->blank) {
> +                        *dst8++ = ((ptr8[0] - header->data_min) * 255) / (header->data_max - header->data_min);
> +                    } else {
> +                        *dst8++ = 0;
> +                    }
> +                    ptr8++;
> +                }
> +            }
> +        } else if (header->bitpix == 16) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst16 = (uint16_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    t16 = AV_RB16(ptr8);
> +                    if (t16 != header->blank) {
> +                        t16 = ((t16 - header->data_min) * 65535) / (header->data_max - header->data_min);
> +                    } else {
> +                        t16 = 0;
> +                    }
> +                    *dst16++ = t16;
> +                    ptr8 += 2;
> +                }
> +            }
> +        } else if (header->bitpix == 32) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst16 = (uint16_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    t32 = AV_RB32(ptr8);
> +                    if (t32 != header->blank) {
> +                        t16 = ((t32 - header->data_min) * 65535) / (header->data_max - header->data_min);
> +                    } else {
> +                        t16 = 0;
> +                    }
> +                    *dst16++ = t16;
> +                    ptr8 += 4;
> +                }
> +            }
> +        } else if (header->bitpix == 64) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst16 = (uint16_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    t64 = AV_RB64(ptr8);
> +                    if (t64 != header->blank) {
> +                        t16 = ((t64 - header->data_min) * 65535) / (header->data_max - header->data_min);
> +                    } else {
> +                        t16 = 0;
> +                    }
> +                    *dst16++ = t16;
> +                    ptr8 += 8;
> +                }
> +            }

Ditto for these four blocks.

> +        } else if (header->bitpix == -32) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst16 = (uint16_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    tflt = av_int2float(AV_RB32(ptr8));
> +                    *dst16++ = ((tflt - header->data_min) * 65535) / (header->data_max - header->data_min);
> +                    ptr8 += 4;
> +                }
> +            }
> +        } else if (header->bitpix == -64) {
> +            for (i = 0; i < avctx->height; i++) {
> +                dst16 = (uint16_t *)(p->data[0] + (avctx->height-i-1) * p->linesize[0]);
> +                for (j = 0; j < avctx->width; j++) {
> +                    tdbl = av_int2double(AV_RB64(ptr8));
> +                    *dst16++ = ((tdbl - header->data_min) * 65535) / (header->data_max - header->data_min);
> +                    ptr8 += 8;
> +                }
> +            }

And ditto for these two, or even possibly these six.

> +        } else {
> +            av_log(avctx, AV_LOG_ERROR, "invalid BITPIX, %d\n", header->bitpix);
> +            return AVERROR_INVALIDDATA;
> +        }
> +    }
> +
> +    p->key_frame = 1;
> +    p->pict_type = AV_PICTURE_TYPE_I;
> +
> +    *got_frame = 1;
> +
> +    return avpkt->size;
> +}
> +
> +AVCodec ff_fits_decoder = {
> +    .name           = "fits",
> +    .type           = AVMEDIA_TYPE_VIDEO,
> +    .id             = AV_CODEC_ID_FITS,
> +    .priv_data_size = sizeof(FITSDecContext),
> +    .decode         = fits_decode_frame,
> +    .capabilities   = AV_CODEC_CAP_DR1,
> +    .long_name      = NULL_IF_CONFIG_SMALL("Flexible Image Transport System")
> +};
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index 0661526..5b99785 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -28,8 +28,8 @@
>  #include "libavutil/version.h"
> 
>  #define LIBAVCODEC_VERSION_MAJOR  57
> -#define LIBAVCODEC_VERSION_MINOR 100
> -#define LIBAVCODEC_VERSION_MICRO 102
> +#define LIBAVCODEC_VERSION_MINOR 101
> +#define LIBAVCODEC_VERSION_MICRO 100
> 
>  #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
>                                                 LIBAVCODEC_VERSION_MINOR, \
> diff --git a/libavformat/img2.c b/libavformat/img2.c
> index 8432cc0..e405df8 100644
> --- a/libavformat/img2.c
> +++ b/libavformat/img2.c
> @@ -80,6 +80,7 @@ const IdStrMap ff_img_tags[] = {
>      { AV_CODEC_ID_XPM,        "xpm"      },
>      { AV_CODEC_ID_XFACE,      "xface"    },
>      { AV_CODEC_ID_XWD,        "xwd"      },
> +    { AV_CODEC_ID_FITS,       "fits"     },
>      { AV_CODEC_ID_NONE,       NULL       }
>  };
> 

Regards,

-- 
  Nicolas George
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