[FFmpeg-devel] avcodec: add PhotoCD decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
Probably need to be applied on top of moflex v2 patch set.
---
 libavcodec/Makefile     |   1 +
 libavcodec/allcodecs.c  |   1 +
 libavcodec/codec_desc.c |   7 +
 libavcodec/codec_id.h   |   1 +
 libavcodec/photocd.c    | 468 ++++++++++++++++++++++++++++++++++++++++
 libavformat/img2.c      |   1 +
 6 files changed, 479 insertions(+)
 create mode 100644 libavcodec/photocd.c

On 8/29/20, Paul B Mahol <onemda@gmail.com> wrote:
> Signed-Goff-by: Paul B Mahol <onemda@gmail.com>
> ---
> Probably need to be applied on top of moflex v2 patch set.
> ---

[...]

> +
> +static av_cold int photocd_decode_init(AVCodecContext *avctx)
> +{
> +    avctx->pix_fmt         = AV_PIX_FMT_YUV420P;
> +    avctx->colorspace      = AVCOL_SPC_BT709;
> +    avctx->color_primaries = AVCOL_PRI_BT709;
> +    avctx->color_trc       = AVCOL_TRC_IEC61966_2_4;
> +    avctx->color_range     = AVCOL_RANGE_MPEG;

Locally changed to JPEG color range, as that is much better looking.

> +
> +    return 0;
> +}
> +
> +static av_cold int photocd_decode_close(AVCodecContext *avctx)
> +{
> +    PhotoCDContext *s = avctx->priv_data;
> +
> +    for (int i = 0; i < 3; i++)
> +        ff_free_vlc(&s->vlc[i]);
> +
> +    return 0;
> +}
> +
> +#define OFFSET(x) offsetof(PhotoCDContext, x)
> +#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
> +
> +static const AVOption options[] = {
> +    { "lowres",  "Lower the decoding resolution by a power of two",
> +        OFFSET(lowres), AV_OPT_TYPE_INT,  { .i64 = 0 }, 0, 4, VD },
> +    { NULL },
> +};
> +
> +static const AVClass photocd_class = {
> +    .class_name = "photocd",
> +    .item_name  = av_default_item_name,
> +    .option     = options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
> +AVCodec ff_photocd_decoder = {
> +    .name           = "photocd",
> +    .type           = AVMEDIA_TYPE_VIDEO,
> +    .id             = AV_CODEC_ID_PHOTOCD,
> +    .priv_data_size = sizeof (PhotoCDContext),
> +    .priv_class     = &photocd_class,
> +    .init           = photocd_decode_init,
> +    .close          = photocd_decode_close,
> +    .decode         = photocd_decode_frame,
> +    .capabilities   = AV_CODEC_CAP_DR1,
> +    .long_name      = NULL_IF_CONFIG_SMALL("Kodak Photo CD"),
> +};
> diff --git a/libavformat/img2.c b/libavformat/img2.c
> index d243d6c125..db37aa7228 100644
> --- a/libavformat/img2.c
> +++ b/libavformat/img2.c
> @@ -55,6 +55,7 @@ const IdStrMap ff_img_tags[] = {
>      { AV_CODEC_ID_TIFF,       "dng"      },
>      { AV_CODEC_ID_SGI,        "sgi"      },
>      { AV_CODEC_ID_PTX,        "ptx"      },
> +    { AV_CODEC_ID_PHOTOCD,    "pcd"      },
>      { AV_CODEC_ID_PCX,        "pcx"      },
>      { AV_CODEC_ID_QDRAW,      "pic"      },
>      { AV_CODEC_ID_QDRAW,      "pct"      },
> --
> 2.17.1
>
>

Paul B Mahol:
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
> Probably need to be applied on top of moflex v2 patch set.
> ---
>  libavcodec/Makefile     |   1 +
>  libavcodec/allcodecs.c  |   1 +
>  libavcodec/codec_desc.c |   7 +
>  libavcodec/codec_id.h   |   1 +
>  libavcodec/photocd.c    | 468 ++++++++++++++++++++++++++++++++++++++++
>  libavformat/img2.c      |   1 +
>  6 files changed, 479 insertions(+)
>  create mode 100644 libavcodec/photocd.c
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 97fbe6b7a9..98f31e246b 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -541,6 +541,7 @@ OBJS-$(CONFIG_PGMYUV_DECODER)          += pnmdec.o pnm.o
>  OBJS-$(CONFIG_PGMYUV_ENCODER)          += pnmenc.o
>  OBJS-$(CONFIG_PGSSUB_DECODER)          += pgssubdec.o
>  OBJS-$(CONFIG_PGX_DECODER)             += pgxdec.o
> +OBJS-$(CONFIG_PHOTOCD_DECODER)         += photocd.o
>  OBJS-$(CONFIG_PICTOR_DECODER)          += pictordec.o cga_data.o
>  OBJS-$(CONFIG_PIXLET_DECODER)          += pixlet.o
>  OBJS-$(CONFIG_PJS_DECODER)             += textdec.o ass.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index 8a4b3fb178..f3572a47e3 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -241,6 +241,7 @@ extern AVCodec ff_pgm_decoder;
>  extern AVCodec ff_pgmyuv_encoder;
>  extern AVCodec ff_pgmyuv_decoder;
>  extern AVCodec ff_pgx_decoder;
> +extern AVCodec ff_photocd_decoder;
>  extern AVCodec ff_pictor_decoder;
>  extern AVCodec ff_pixlet_decoder;
>  extern AVCodec ff_png_encoder;
> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> index ceef244ebf..9e73dcba27 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -1791,6 +1791,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
>          .long_name = NULL_IF_CONFIG_SMALL("MobiClip Video"),
>          .props     = AV_CODEC_PROP_LOSSY,
>      },
> +    {
> +        .id        = AV_CODEC_ID_PHOTOCD,
> +        .type      = AVMEDIA_TYPE_VIDEO,
> +        .name      = "photocd",
> +        .long_name = NULL_IF_CONFIG_SMALL("Kodak Photo CD"),
> +        .props     = AV_CODEC_PROP_LOSSY,
> +    },
>  
>      /* various PCM "codecs" */
>      {
> diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
> index 19d5014bb4..e4eca5d580 100644
> --- a/libavcodec/codec_id.h
> +++ b/libavcodec/codec_id.h
> @@ -297,6 +297,7 @@ enum AVCodecID {
>      AV_CODEC_ID_NOTCHLC,
>      AV_CODEC_ID_PFM,
>      AV_CODEC_ID_MOBICLIP,
> +    AV_CODEC_ID_PHOTOCD,
>  
>      /* various PCM "codecs" */
>      AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
> diff --git a/libavcodec/photocd.c b/libavcodec/photocd.c
> new file mode 100644
> index 0000000000..50584ac980
> --- /dev/null
> +++ b/libavcodec/photocd.c
> @@ -0,0 +1,468 @@
> +/*
> + * Kodak PhotoCD (a.k.a. ImagePac) image decoder
> + *
> + * Copyright (c) 1996-2002 Gerd Knorr
> + * Copyright (c) 2010 Kenneth Vermeirsch
> + * Copyright (c) 2020 Paul B Mahol
> + *
> + * 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
> + * Kodak PhotoCD (a.k.a. ImagePac) image decoder
> + *
> + * Supports resolutions up to 3072x2048.
> + */
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/opt.h"
> +#include "avcodec.h"
> +#include "bytestream.h"
> +#include "get_bits.h"
> +#include "internal.h"
> +
> +typedef struct PhotoCDContext {
> +    AVClass *class;
> +    int      lowres;
> +
> +    GetByteContext gb;
> +    int      thumbnails;  //* number of thumbnails; 0 for normal image */
> +    int      resolution;
> +    int      orientation;
> +
> +    int      streampos;
> +
> +    uint8_t  bits[256];
> +    uint16_t codes[256];
> +    uint8_t  syms[256];
> +
> +    VLC      vlc[3];
> +} PhotoCDContext;
> +
> +typedef struct ImageInfo {
> +    uint32_t start;
> +    uint16_t width, height;
> +} ImageInfo;
> +
> +static const ImageInfo img_info[6] = {
> +    {8192,    192, 128},
> +    {47104,   384, 256},
> +    {196608,  768, 512},
> +    {0,      1536, 1024},
> +    {0,      3072, 2048},
> +    {0,      6144, 4096},
> +};
> +
> +static av_always_inline void interp_lowres(PhotoCDContext *s, AVFrame *picture,
> +                                           int width, int height)
> +{
> +    GetByteContext *gb = &s->gb;
> +    int start = s->streampos + img_info[2].start;
> +    uint8_t *ptr, *ptr1, *ptr2;
> +    uint8_t *dest;
> +    int fill;
> +
> +    ptr  = picture->data[0];
> +    ptr1 = picture->data[1];
> +    ptr2 = picture->data[2];
> +
> +    bytestream2_seek(gb, start, SEEK_SET);
> +
> +    for (int y = 0; y < height; y += 2) {
> +        dest = ptr;
> +        for (int x = 0; x < width - 1; x++) {
> +            fill = bytestream2_get_byte(gb);
> +            *(dest++) = fill;
> +            *(dest++) = (fill + bytestream2_peek_byte(gb) + 1) >> 1;
> +        }
> +        fill      = bytestream2_get_byte(gb);
> +        *(dest++) = fill;
> +        *(dest++) = fill;
> +
> +        ptr += picture->linesize[0] << 1;
> +
> +        dest = ptr;
> +        for (int x = 0; x < width - 1; x++) {
> +            fill = bytestream2_get_byte(gb);
> +            *(dest++) =  fill;
> +            *(dest++) = (fill + bytestream2_peek_byte(gb) + 1) >> 1;
> +        }
> +        fill      = bytestream2_get_byte(gb);
> +        *(dest++) = fill;
> +        *(dest++) = fill;
> +
> +        ptr += picture->linesize[0] << 1;
> +
> +        dest = ptr1;
> +        for (int x = 0; x < (width >> 1) - 1; x++) {
> +            fill = bytestream2_get_byte(gb);
> +            *(dest++) =  fill;
> +            *(dest++) = (fill + bytestream2_peek_byte(gb) + 1) >> 1;
> +        }
> +        fill      = bytestream2_get_byte(gb);
> +        *(dest++) = fill;
> +        *(dest++) = fill;
> +
> +        ptr1 += picture->linesize[1] << 1;
> +
> +        dest = ptr2;
> +        for (int x = 0; x < (width >> 1) - 1; x++) {
> +            fill = bytestream2_get_byte(gb);
> +            *(dest++) =  fill;
> +            *(dest++) = (fill + bytestream2_peek_byte(gb) + 1) >> 1;
> +        }
> +        fill      = bytestream2_get_byte(gb);
> +        *(dest++) = fill;
> +        *(dest++) = fill;
> +
> +        ptr2 += picture->linesize[2] << 1;
> +    }
> +
> +    s->streampos += bytestream2_tell(gb) - start;
> +}
> +
> +static void interp_lines(uint8_t *ptr, int linesize, int width, int height)
> +{
> +    uint8_t *src1, *src2, *dest;
> +    int x;
> +
> +    for (int y = 0; y < height - 2; y += 2) {
> +        src1 = ptr;
> +        dest = src1 + linesize;
> +        src2 = dest + linesize;
> +        for (x = 0; x < width - 2; x += 2) {
> +            dest[x]     = (src1[x] + src2[x] + 1) >> 1;
> +            dest[x + 1] = (src1[x] + src2[x] + src1[x + 2] + src2[x + 2] + 2) >> 2;
> +        }
> +        dest[x] = dest[x + 1] = (src1[x] + src2[x] + 1) >> 1;
> +
> +        ptr += linesize << 1;
> +    }
> +
> +    src1 = ptr;
> +    dest = ptr + linesize;
> +    for (x = 0; x < width - 2; x += 2) {
> +        dest[x]     = src1[x];
> +        dest[x + 1] = (src1[x] + src1[x + 2] + 1) >> 1;
> +    }
> +    dest[x] = dest[x + 1] = src1[x];
> +}
> +
> +static void interp_pixels(uint8_t *ptr, int linesize, int width, int height)
> +{
> +    uint8_t *src, *dest;
> +
> +    for (int y = height - 2; y >= 0; y -= 2) {
> +        src  = ptr + (y >> 1) * linesize;
> +        dest = ptr +  y       * linesize;
> +
> +        dest[width - 2] = dest[width - 1] = src[(width >> 1) - 1];
> +        for (int x = width - 4; x >= 0; x -= 2) {
> +            dest[x]     =  src[x >> 1];
> +            dest[x + 1] = (src[x >> 1] + src[(x >> 1) + 1] + 1) >> 1;
> +        }
> +    }
> +}
> +
> +static int read_hufftable(AVCodecContext *avctx, VLC *vlc)
> +{
> +    PhotoCDContext *s = avctx->priv_data;
> +    GetByteContext *gb = &s->gb;
> +    int start = s->streampos;
> +    int count, ret;
> +
> +    bytestream2_seek(gb, start, SEEK_SET);
> +
> +    count = bytestream2_get_byte(gb) + 1;
> +

With this information you can check once whether there is enough data
left, allowing you to use the unchecked versions of the bytestream2 API.

> +    ff_free_vlc(vlc);
> +
> +    for (int j = 0; j < count; j++) {
> +        const int bit  = bytestream2_get_byte(gb) + 1;
> +        const int code = bytestream2_get_be16(gb) >> (16 - bit);

You are using bit here before having validated it.

> +        const int sym  = bytestream2_get_byte(gb);
> +
> +        if (bit > 16)
> +            return AVERROR_INVALIDDATA;
> +
> +        s->bits[j]  = bit;
> +        s->codes[j] = code;
> +        s->syms[j]  = sym;
> +    }
> +
> +    ret = ff_init_vlc_sparse(vlc, 12, count,
> +                             s->bits,  sizeof(*s->bits),  sizeof(*s->bits),
> +                             s->codes, sizeof(*s->codes), sizeof(*s->codes),
> +                             s->syms,  sizeof(*s->syms),  sizeof(*s->syms), 0);
> +
> +    s->streampos = bytestream2_tell(gb);
> +
> +    return ret;
> +}
> +
> +static int decode_huff(AVCodecContext *avctx, AVFrame *frame,
> +                       int target_res, int curr_res)
> +{
> +    PhotoCDContext *s = avctx->priv_data;
> +    GetBitContext g;
> +    GetByteContext *gb = &s->gb;
> +    int ret, y = 0, type, height, y2;
> +    int start = s->streampos;
> +    unsigned shiftreg, bit;
> +    const int scaling = target_res - curr_res;
> +    const uint8_t type2idx[] = { 0, 0xff, 1, 2 };
> +
> +    bytestream2_seek(gb, start, SEEK_SET);
> +    ret = init_get_bits8(&g, gb->buffer, bytestream2_get_bytes_left(gb));
> +    if (ret < 0)
> +        return ret;
> +
> +    height = img_info[curr_res].height;
> +    y2 = avctx->height >> scaling;
> +
> +    while (y < height) {
> +        uint8_t *data;
> +        int x2, idx;
> +
> +        bit = 0;
> +        for (; get_bits_left(&g) > 0;) {
> +            if ((show_bits_long(&g, 32) & 0x00fff000) == 0xfff000)
> +                break;
> +            skip_bits(&g, 8);
> +        }
> +
> +        shiftreg = show_bits_long(&g, 32) & 0xffffff00;
> +        while (shiftreg != 0xfffffe00) {
> +            if (get_bits_left(&g) <= 0)
> +                return AVERROR_INVALIDDATA;
> +            skip_bits(&g, 1);
> +            shiftreg = show_bits_long(&g, 32) & 0xffffff00;
> +        }
> +        skip_bits(&g, 16);
> +        y = (show_bits_long(&g, 32) >> 9) & 0x1fff;
> +        skip_bits(&g, 8);
> +        if (y >= height)
> +            break;
> +        type = get_bits(&g, 2);
> +        skip_bits(&g, 14);
> +
> +        if (type == 1)
> +            return AVERROR_INVALIDDATA;
> +        idx  = type2idx[type];
> +
> +        data = frame->data[idx] + (y >> !!idx) * frame->linesize[idx];
> +
> +        x2 = avctx->width >> (scaling + !!idx);
> +        for (int x = 0; x < x2; x++) {
> +            int m;
> +
> +            if (get_bits_left(&g) <= 0)
> +                return AVERROR_INVALIDDATA;
> +            m = get_vlc2(&g, s->vlc[idx].table, s->vlc[idx].bits, 2);
> +            if (m < 0)
> +                return AVERROR_INVALIDDATA;
> +            m = sign_extend(m, 8);
> +            data[x] = av_clip_uint8(data[x] + m);
> +        }
> +    }
> +
> +    s->streampos += (get_bits_count(&g) + 7) >> 3;
> +    s->streampos  = (s->streampos + 0x6000 + 2047) & ~0x7ff;
> +
> +    return 0;
> +}
> +
> +static int photocd_decode_frame(AVCodecContext *avctx, void *data,
> +                                int *got_frame, AVPacket *avpkt)
> +{
> +    PhotoCDContext *s = avctx->priv_data;
> +    const uint8_t *buf = avpkt->data;
> +    GetByteContext *gb = &s->gb;
> +    AVFrame *p = data;
> +    uint8_t *ptr, *ptr1, *ptr2;
> +    int ret;
> +
> +    if (avpkt->size < img_info[0].start)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (!memcmp("PCD_OPA", buf, 7)) {
> +        s->thumbnails = AV_RL16(buf + 10);
> +        av_log(avctx, AV_LOG_WARNING, "this is a thumbnails file, "
> +               "reading first thumbnail only\n");
> +    } else if (avpkt->size < 786432) {
> +        return AVERROR_INVALIDDATA;
> +    } else if (memcmp("PCD_IPI", buf + 0x800, 7)) {
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    s->orientation = s->thumbnails ? buf[12] & 3 : buf[0x48] & 3;
> +
> +    if (s->thumbnails)
> +        s->resolution = 0;
> +    else if (avpkt->size <= 788480)
> +        s->resolution = 2;
> +    else
> +        s->resolution = av_clip(4 - s->lowres, 0, 4);
> +
> +    avctx->width  = img_info[s->resolution].width;
> +    avctx->height = img_info[s->resolution].height;
> +
> +    if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
> +        return ret;
> +    p->pict_type = AV_PICTURE_TYPE_I;
> +    p->key_frame = 1;
> +
> +    bytestream2_init(gb, avpkt->data, avpkt->size);
> +
> +    if (s->resolution < 3) {
> +        ptr  = p->data[0];
> +        ptr1 = p->data[1];
> +        ptr2 = p->data[2];
> +
> +        if (s->thumbnails) {
> +            bytestream2_seek(gb, 10240, SEEK_SET);
> +        } else {
> +            bytestream2_seek(gb, img_info[s->resolution].start, SEEK_SET);
> +        }
> +
> +        for (int y = 0; y < avctx->height; y += 2) {
> +            bytestream2_get_buffer(gb, ptr, avctx->width);
> +            ptr += p->linesize[0];
> +
> +            bytestream2_get_buffer(gb, ptr, avctx->width);
> +            ptr += p->linesize[0];
> +
> +            bytestream2_get_buffer(gb, ptr1, avctx->width >> 1);
> +            ptr1 += p->linesize[1];
> +
> +            bytestream2_get_buffer(gb, ptr2, avctx->width >> 1);
> +            ptr2 += p->linesize[2];
> +        }
> +    } else {
> +        s->streampos = 0;
> +        ptr  = p->data[0];
> +        ptr1 = p->data[1];
> +        ptr2 = p->data[2];
> +
> +        interp_lowres(s, p, img_info[2].width, img_info[2].height);
> +
> +        interp_lines(ptr1, p->linesize[1], img_info[2].width, img_info[2].height);
> +        interp_lines(ptr2, p->linesize[2], img_info[2].width, img_info[2].height);
> +
> +        if (s->resolution == 4) {
> +            interp_pixels(ptr1, p->linesize[1], img_info[3].width, img_info[3].height);
> +            interp_lines (ptr1, p->linesize[1], img_info[3].width, img_info[3].height);
> +            interp_pixels(ptr2, p->linesize[2], img_info[3].width, img_info[3].height);
> +            interp_lines (ptr2, p->linesize[2], img_info[3].width, img_info[3].height);
> +        }
> +
> +        interp_lines(ptr, p->linesize[0], img_info[3].width, img_info[3].height);
> +
> +        s->streampos = 0xc2000;
> +        for (int n = 0; n < 3; n++) {
> +            if ((ret = read_hufftable(avctx, &s->vlc[n])) < 0)
> +                return ret;
> +        }
> +        s->streampos = (s->streampos + 2047) & ~0x3ff;
> +        if (decode_huff(avctx, p, s->resolution, 3) < 0)
> +            return AVERROR_INVALIDDATA;
> +
> +        if (s->resolution == 4) {
> +            interp_pixels(ptr, p->linesize[0], img_info[4].width, img_info[4].height);
> +            interp_lines (ptr, p->linesize[0], img_info[4].width, img_info[4].height);
> +
> +            for (int n = 0; n < 3; n++) {
> +                if ((ret = read_hufftable(avctx, &s->vlc[n])) < 0)
> +                    return ret;
> +            }
> +            s->streampos = (s->streampos + 2047) & ~0x3ff;
> +            if (decode_huff(avctx, p, 4, 4) < 0)
> +                return AVERROR_INVALIDDATA;
> +        }
> +    }
> +
> +    {
> +        ptr1 = p->data[1];
> +        ptr2 = p->data[2];
> +
> +        for (int y = 0; y < avctx->height >> 1; y++) {
> +            for (int x = 0; x < avctx->width >> 1; x++) {
> +                ptr1[x] = av_clip_uint8(ptr1[x] - 28);
> +                ptr2[x] = av_clip_uint8(ptr2[x] - 9);
> +            }
> +
> +            ptr1 += p->linesize[1];
> +            ptr2 += p->linesize[2];
> +        }
> +    }
> +
> +    *got_frame = 1;
> +
> +    return 0;
> +}
> +
> +static av_cold int photocd_decode_init(AVCodecContext *avctx)
> +{
> +    avctx->pix_fmt         = AV_PIX_FMT_YUV420P;
> +    avctx->colorspace      = AVCOL_SPC_BT709;
> +    avctx->color_primaries = AVCOL_PRI_BT709;
> +    avctx->color_trc       = AVCOL_TRC_IEC61966_2_4;
> +    avctx->color_range     = AVCOL_RANGE_MPEG;
> +
> +    return 0;
> +}
> +
> +static av_cold int photocd_decode_close(AVCodecContext *avctx)
> +{
> +    PhotoCDContext *s = avctx->priv_data;
> +
> +    for (int i = 0; i < 3; i++)
> +        ff_free_vlc(&s->vlc[i]);
> +
> +    return 0;
> +}
> +
> +#define OFFSET(x) offsetof(PhotoCDContext, x)
> +#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
> +
> +static const AVOption options[] = {
> +    { "lowres",  "Lower the decoding resolution by a power of two",
> +        OFFSET(lowres), AV_OPT_TYPE_INT,  { .i64 = 0 }, 0, 4, VD },
> +    { NULL },
> +};
> +
> +static const AVClass photocd_class = {
> +    .class_name = "photocd",
> +    .item_name  = av_default_item_name,
> +    .option     = options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
> +AVCodec ff_photocd_decoder = {
> +    .name           = "photocd",
> +    .type           = AVMEDIA_TYPE_VIDEO,
> +    .id             = AV_CODEC_ID_PHOTOCD,
> +    .priv_data_size = sizeof (PhotoCDContext),
> +    .priv_class     = &photocd_class,
> +    .init           = photocd_decode_init,
> +    .close          = photocd_decode_close,
> +    .decode         = photocd_decode_frame,
> +    .capabilities   = AV_CODEC_CAP_DR1,
> +    .long_name      = NULL_IF_CONFIG_SMALL("Kodak Photo CD"),
> +};
> diff --git a/libavformat/img2.c b/libavformat/img2.c
> index d243d6c125..db37aa7228 100644
> --- a/libavformat/img2.c
> +++ b/libavformat/img2.c
> @@ -55,6 +55,7 @@ const IdStrMap ff_img_tags[] = {
>      { AV_CODEC_ID_TIFF,       "dng"      },
>      { AV_CODEC_ID_SGI,        "sgi"      },
>      { AV_CODEC_ID_PTX,        "ptx"      },
> +    { AV_CODEC_ID_PHOTOCD,    "pcd"      },
>      { AV_CODEC_ID_PCX,        "pcx"      },
>      { AV_CODEC_ID_QDRAW,      "pic"      },
>      { AV_CODEC_ID_QDRAW,      "pct"      },
>

On 8/30/20, Andreas Rheinhardt <andreas.rheinhardt@gmail.com> wrote:
[...]
>> +static int read_hufftable(AVCodecContext *avctx, VLC *vlc)
>> +{
>> +    PhotoCDContext *s = avctx->priv_data;
>> +    GetByteContext *gb = &s->gb;
>> +    int start = s->streampos;
>> +    int count, ret;
>> +
>> +    bytestream2_seek(gb, start, SEEK_SET);
>> +
>> +    count = bytestream2_get_byte(gb) + 1;
>> +
>
> With this information you can check once whether there is enough data
> left, allowing you to use the unchecked versions of the bytestream2 API.

Fixed locally.

>
>> +    ff_free_vlc(vlc);
>> +
>> +    for (int j = 0; j < count; j++) {
>> +        const int bit  = bytestream2_get_byte(gb) + 1;
>> +        const int code = bytestream2_get_be16(gb) >> (16 - bit);
>
> You are using bit here before having validated it.

Fixed locally.

[...]

On 8/30/20, Paul B Mahol <onemda@gmail.com> wrote:
> On 8/30/20, Andreas Rheinhardt <andreas.rheinhardt@gmail.com> wrote:
> [...]
>>> +static int read_hufftable(AVCodecContext *avctx, VLC *vlc)
>>> +{
>>> +    PhotoCDContext *s = avctx->priv_data;
>>> +    GetByteContext *gb = &s->gb;
>>> +    int start = s->streampos;
>>> +    int count, ret;
>>> +
>>> +    bytestream2_seek(gb, start, SEEK_SET);
>>> +
>>> +    count = bytestream2_get_byte(gb) + 1;
>>> +
>>
>> With this information you can check once whether there is enough data
>> left, allowing you to use the unchecked versions of the bytestream2 API.
>
> Fixed locally.
>
>>
>>> +    ff_free_vlc(vlc);
>>> +
>>> +    for (int j = 0; j < count; j++) {
>>> +        const int bit  = bytestream2_get_byte(gb) + 1;
>>> +        const int code = bytestream2_get_be16(gb) >> (16 - bit);
>>
>> You are using bit here before having validated it.
>
> Fixed locally.
>
> [...]
>


Gonna apply with few other small changes.