OpenEXR decoder

Additional fixes and enhancements by Vittorio Giovara, Gonzalo Garramuno,
Nicolas George, Paul B Mahol and Michael Niedermayer.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

1 files changed, 1348 insertions, 0 deletions

diff --git a/libavcodec/exr.c b/libavcodec/exr.c
new file mode 100644
index 0000000000..9f60cc6fb1
--- /dev/null
+++ b/libavcodec/exr.c
@@ -0,0 +1,1348 @@
+/*
+ * OpenEXR (.exr) image decoder
+ * Copyright (c) 2009 Jimmy Christensen
+ *
+ * This file is part of Libav
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * OpenEXR decoder
+ * @author Jimmy Christensen
+ *
+ * For more information on the OpenEXR format, visit:
+ *  http://openexr.com/
+ *
+ * exr_flt2uint() and exr_halflt2uint() is credited to  Reimar Döffinger
+ */
+
+#include <zlib.h>
+
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "get_bits.h"
+#include "internal.h"
+#include "mathops.h"
+#include "thread.h"
+
+enum ExrCompr {
+    EXR_RAW,
+    EXR_RLE,
+    EXR_ZIP1,
+    EXR_ZIP16,
+    EXR_PIZ,
+    EXR_PXR24,
+    EXR_B44,
+    EXR_B44A,
+    EXR_UNKN,
+};
+
+enum ExrPixelType {
+    EXR_UINT,
+    EXR_HALF,
+    EXR_FLOAT,
+    EXR_UNKNOWN,
+};
+
+typedef struct EXRChannel {
+    int xsub, ysub;
+    enum ExrPixelType pixel_type;
+} EXRChannel;
+
+typedef struct EXRThreadData {
+    uint8_t *uncompressed_data;
+    int uncompressed_size;
+
+    uint8_t *tmp;
+    int tmp_size;
+
+    uint8_t *bitmap;
+    uint16_t *lut;
+} EXRThreadData;
+
+typedef struct EXRContext {
+    AVClass *class;
+    AVFrame *picture;
+    AVCodecContext *avctx;
+
+    enum ExrCompr compression;
+    enum ExrPixelType pixel_type;
+    int channel_offsets[4]; // 0 = red, 1 = green, 2 = blue and 3 = alpha
+    const AVPixFmtDescriptor *desc;
+
+    int w, h;
+    uint32_t xmax, xmin;
+    uint32_t ymax, ymin;
+    uint32_t xdelta, ydelta;
+    int ysize;
+
+    uint64_t scan_line_size;
+    int scan_lines_per_block;
+
+    GetByteContext gb;
+    const uint8_t *buf;
+    int buf_size;
+
+    EXRChannel *channels;
+    int nb_channels;
+
+    EXRThreadData *thread_data;
+
+    const char *layer;
+} EXRContext;
+
+/**
+ * Convert from 32-bit float as uint32_t to uint16_t.
+ *
+ * @param v 32-bit float
+ *
+ * @return normalized 16-bit unsigned int
+ */
+static inline uint16_t exr_flt2uint(uint32_t v)
+{
+    unsigned int exp = v >> 23;
+    // "HACK": negative values result in exp<  0, so clipping them to 0
+    // is also handled by this condition, avoids explicit check for sign bit.
+    if (exp <= 127 + 7 - 24) // we would shift out all bits anyway
+        return 0;
+    if (exp >= 127)
+        return 0xffff;
+    v &= 0x007fffff;
+    return (v + (1 << 23)) >> (127 + 7 - exp);
+}
+
+/**
+ * Convert from 16-bit float as uint16_t to uint16_t.
+ *
+ * @param v 16-bit float
+ *
+ * @return normalized 16-bit unsigned int
+ */
+static inline uint16_t exr_halflt2uint(uint16_t v)
+{
+    unsigned exp = 14 - (v >> 10);
+    if (exp >= 14) {
+        if (exp == 14)
+            return (v >> 9) & 1;
+        else
+            return (v & 0x8000) ? 0 : 0xffff;
+    }
+    v <<= 6;
+    return (v + (1 << 16)) >> (exp + 1);
+}
+
+static void predictor(uint8_t *src, int size)
+{
+    uint8_t *t    = src + 1;
+    uint8_t *stop = src + size;
+
+    while (t < stop) {
+        int d = (int) t[-1] + (int) t[0] - 128;
+        t[0] = d;
+        ++t;
+    }
+}
+
+static void reorder_pixels(uint8_t *src, uint8_t *dst, int size)
+{
+    const int8_t *t1 = src;
+    const int8_t *t2 = src + (size + 1) / 2;
+    int8_t *s        = dst;
+    int8_t *stop     = s + size;
+
+    while (1) {
+        if (s < stop)
+            *(s++) = *(t1++);
+        else
+            break;
+
+        if (s < stop)
+            *(s++) = *(t2++);
+        else
+            break;
+    }
+}
+
+static int zip_uncompress(const uint8_t *src, int compressed_size,
+                          int uncompressed_size, EXRThreadData *td)
+{
+    unsigned long dest_len = uncompressed_size;
+
+    if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
+        dest_len != uncompressed_size)
+        return AVERROR_INVALIDDATA;
+
+    predictor(td->tmp, uncompressed_size);
+    reorder_pixels(td->tmp, td->uncompressed_data, uncompressed_size);
+
+    return 0;
+}
+
+static int rle_uncompress(const uint8_t *src, int compressed_size,
+                          int uncompressed_size, EXRThreadData *td)
+{
+    uint8_t *d      = td->tmp;
+    const int8_t *s = src;
+    int ssize       = compressed_size;
+    int dsize       = uncompressed_size;
+    uint8_t *dend   = d + dsize;
+    int count;
+
+    while (ssize > 0) {
+        count = *s++;
+
+        if (count < 0) {
+            count = -count;
+
+            if ((dsize -= count) < 0 ||
+                (ssize -= count + 1) < 0)
+                return AVERROR_INVALIDDATA;
+
+            while (count--)
+                *d++ = *s++;
+        } else {
+            count++;
+
+            if ((dsize -= count) < 0 ||
+                (ssize -= 2) < 0)
+                return AVERROR_INVALIDDATA;
+
+            while (count--)
+                *d++ = *s;
+
+            s++;
+        }
+    }
+
+    if (dend != d)
+        return AVERROR_INVALIDDATA;
+
+    predictor(td->tmp, uncompressed_size);
+    reorder_pixels(td->tmp, td->uncompressed_data, uncompressed_size);
+
+    return 0;
+}
+
+#define USHORT_RANGE (1 << 16)
+#define BITMAP_SIZE  (1 << 13)
+
+static uint16_t reverse_lut(const uint8_t *bitmap, uint16_t *lut)
+{
+    int i, k = 0;
+
+    for (i = 0; i < USHORT_RANGE; i++)
+        if ((i == 0) || (bitmap[i >> 3] & (1 << (i & 7))))
+            lut[k++] = i;
+
+    i = k - 1;
+
+    memset(lut + k, 0, (USHORT_RANGE - k) * 2);
+
+    return i;
+}
+
+static void apply_lut(const uint16_t *lut, uint16_t *dst, int dsize)
+{
+    int i;
+
+    for (i = 0; i < dsize; ++i)
+        dst[i] = lut[dst[i]];
+}
+
+#define HUF_ENCBITS 16  // literal (value) bit length
+#define HUF_DECBITS 14  // decoding bit size (>= 8)
+
+#define HUF_ENCSIZE ((1 << HUF_ENCBITS) + 1)  // encoding table size
+#define HUF_DECSIZE (1 << HUF_DECBITS)        // decoding table size
+#define HUF_DECMASK (HUF_DECSIZE - 1)
+
+typedef struct HufDec {
+    int len;
+    int lit;
+    int *p;
+} HufDec;
+
+static void huf_canonical_code_table(uint64_t *hcode)
+{
+    uint64_t c, n[59] = { 0 };
+    int i;
+
+    for (i = 0; i < HUF_ENCSIZE; ++i)
+        n[hcode[i]] += 1;
+
+    c = 0;
+    for (i = 58; i > 0; --i) {
+        uint64_t nc = ((c + n[i]) >> 1);
+        n[i] = c;
+        c    = nc;
+    }
+
+    for (i = 0; i < HUF_ENCSIZE; ++i) {
+        int l = hcode[i];
+
+        if (l > 0)
+            hcode[i] = l | (n[l]++ << 6);
+    }
+}
+
+#define SHORT_ZEROCODE_RUN  59
+#define LONG_ZEROCODE_RUN   63
+#define SHORTEST_LONG_RUN   (2 + LONG_ZEROCODE_RUN - SHORT_ZEROCODE_RUN)
+#define LONGEST_LONG_RUN    (255 + SHORTEST_LONG_RUN)
+
+static int huf_unpack_enc_table(GetByteContext *gb,
+                                int32_t im, int32_t iM, uint64_t *hcode)
+{
+    GetBitContext gbit;
+
+    init_get_bits8(&gbit, gb->buffer, bytestream2_get_bytes_left(gb));
+
+    for (; im <= iM; im++) {
+        uint64_t l = hcode[im] = get_bits(&gbit, 6);
+
+        if (l == LONG_ZEROCODE_RUN) {
+            int zerun = get_bits(&gbit, 8) + SHORTEST_LONG_RUN;
+
+            if (im + zerun > iM + 1)
+                return AVERROR_INVALIDDATA;
+
+            while (zerun--)
+                hcode[im++] = 0;
+
+            im--;
+        } else if (l >= SHORT_ZEROCODE_RUN) {
+            int zerun = l - SHORT_ZEROCODE_RUN + 2;
+
+            if (im + zerun > iM + 1)
+                return AVERROR_INVALIDDATA;
+
+            while (zerun--)
+                hcode[im++] = 0;
+
+            im--;
+        }
+    }
+
+    bytestream2_skip(gb, (get_bits_count(&gbit) + 7) / 8);
+    huf_canonical_code_table(hcode);
+
+    return 0;
+}
+
+static int huf_build_dec_table(const uint64_t *hcode, int im,
+                               int iM, HufDec *hdecod)
+{
+    for (; im <= iM; im++) {
+        uint64_t c = hcode[im] >> 6;
+        int i, l = hcode[im] & 63;
+
+        if (c >> l)
+            return AVERROR_INVALIDDATA;
+
+        if (l > HUF_DECBITS) {
+            HufDec *pl = hdecod + (c >> (l - HUF_DECBITS));
+            if (pl->len)
+                return AVERROR_INVALIDDATA;
+
+            pl->lit++;
+
+            pl->p = av_realloc(pl->p, pl->lit * sizeof(int));
+            if (!pl->p)
+                return AVERROR(ENOMEM);
+
+            pl->p[pl->lit - 1] = im;
+        } else if (l) {
+            HufDec *pl = hdecod + (c << (HUF_DECBITS - l));
+
+            for (i = 1 << (HUF_DECBITS - l); i > 0; i--, pl++) {
+                if (pl->len || pl->p)
+                    return AVERROR_INVALIDDATA;
+                pl->len = l;
+                pl->lit = im;
+            }
+        }
+    }
+
+    return 0;
+}
+
+#define get_char(c, lc, gb)                                                   \
+{                                                                             \
+        c   = (c << 8) | bytestream2_get_byte(gb);                            \
+        lc += 8;                                                              \
+}
+
+#define get_code(po, rlc, c, lc, gb, out, oe)                                 \
+{                                                                             \
+        if (po == rlc) {                                                      \
+            if (lc < 8)                                                       \
+                get_char(c, lc, gb);                                          \
+            lc -= 8;                                                          \
+                                                                              \
+            cs = c >> lc;                                                     \
+                                                                              \
+            if (out + cs > oe)                                                \
+                return AVERROR_INVALIDDATA;                                   \
+                                                                              \
+            s = out[-1];                                                      \
+                                                                              \
+            while (cs-- > 0)                                                  \
+                *out++ = s;                                                   \
+        } else if (out < oe) {                                                \
+            *out++ = po;                                                      \
+        } else {                                                              \
+            return AVERROR_INVALIDDATA;                                       \
+        }                                                                     \
+}
+
+static int huf_decode(const uint64_t *hcode, const HufDec *hdecod,
+                      GetByteContext *gb, int nbits,
+                      int rlc, int no, uint16_t *out)
+{
+    uint64_t c        = 0;
+    uint16_t *outb    = out;
+    uint16_t *oe      = out + no;
+    const uint8_t *ie = gb->buffer + (nbits + 7) / 8; // input byte size
+    uint8_t cs, s;
+    int i, lc = 0;
+
+    while (gb->buffer < ie) {
+        get_char(c, lc, gb);
+
+        while (lc >= HUF_DECBITS) {
+            const HufDec pl = hdecod[(c >> (lc - HUF_DECBITS)) & HUF_DECMASK];
+
+            if (pl.len) {
+                lc -= pl.len;
+                get_code(pl.lit, rlc, c, lc, gb, out, oe);
+            } else {
+                int j;
+
+                if (!pl.p)
+                    return AVERROR_INVALIDDATA;
+
+                for (j = 0; j < pl.lit; j++) {
+                    int l = hcode[pl.p[j]] & 63;
+
+                    while (lc < l && bytestream2_get_bytes_left(gb) > 0)
+                        get_char(c, lc, gb);
+
+                    if (lc >= l) {
+                        if ((hcode[pl.p[j]] >> 6) ==
+                            ((c >> (lc - l)) & ((1LL << l) - 1))) {
+                            lc -= l;
+                            get_code(pl.p[j], rlc, c, lc, gb, out, oe);
+                            break;
+                        }
+                    }
+                }
+
+                if (j == pl.lit)
+                    return AVERROR_INVALIDDATA;
+            }
+        }
+    }
+
+    i   = (8 - nbits) & 7;
+    c >>= i;
+    lc -= i;
+
+    while (lc > 0) {
+        const HufDec pl = hdecod[(c << (HUF_DECBITS - lc)) & HUF_DECMASK];
+
+        if (pl.len) {
+            lc -= pl.len;
+            get_code(pl.lit, rlc, c, lc, gb, out, oe);
+        } else {
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
+    if (out - outb != no)
+        return AVERROR_INVALIDDATA;
+    return 0;
+}
+
+static int huf_uncompress(GetByteContext *gb,
+                          uint16_t *dst, int dst_size)
+{
+    int32_t src_size, im, iM;
+    uint32_t nBits;
+    uint64_t *freq;
+    HufDec *hdec;
+    int ret, i;
+
+    src_size = bytestream2_get_le32(gb);
+    im       = bytestream2_get_le32(gb);
+    iM       = bytestream2_get_le32(gb);
+    bytestream2_skip(gb, 4);
+    nBits = bytestream2_get_le32(gb);
+    if (im < 0 || im >= HUF_ENCSIZE ||
+        iM < 0 || iM >= HUF_ENCSIZE ||
+        src_size < 0)
+        return AVERROR_INVALIDDATA;
+
+    bytestream2_skip(gb, 4);
+
+    freq = av_mallocz_array(HUF_ENCSIZE, sizeof(*freq));
+    hdec = av_mallocz_array(HUF_DECSIZE, sizeof(*hdec));
+    if (!freq || !hdec) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    if ((ret = huf_unpack_enc_table(gb, im, iM, freq)) < 0)
+        goto fail;
+
+    if (nBits > 8 * bytestream2_get_bytes_left(gb)) {
+        ret = AVERROR_INVALIDDATA;
+        goto fail;
+    }
+
+    if ((ret = huf_build_dec_table(freq, im, iM, hdec)) < 0)
+        goto fail;
+    ret = huf_decode(freq, hdec, gb, nBits, iM, dst_size, dst);
+
+fail:
+    for (i = 0; i < HUF_DECSIZE; i++)
+        if (hdec)
+            av_freep(&hdec[i].p);
+
+    av_free(freq);
+    av_free(hdec);
+
+    return ret;
+}
+
+static inline void wdec14(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
+{
+    int16_t ls = l;
+    int16_t hs = h;
+    int hi     = hs;
+    int ai     = ls + (hi & 1) + (hi >> 1);
+    int16_t as = ai;
+    int16_t bs = ai - hi;
+
+    *a = as;
+    *b = bs;
+}
+
+#define NBITS      16
+#define A_OFFSET  (1 << (NBITS - 1))
+#define MOD_MASK  ((1 << NBITS) - 1)
+
+static inline void wdec16(uint16_t l, uint16_t h, uint16_t *a, uint16_t *b)
+{
+    int m  = l;
+    int d  = h;
+    int bb = (m - (d >> 1)) & MOD_MASK;
+    int aa = (d + bb - A_OFFSET) & MOD_MASK;
+    *b = bb;
+    *a = aa;
+}
+
+static void wav_decode(uint16_t *in, int nx, int ox,
+                       int ny, int oy, uint16_t mx)
+{
+    int w14 = (mx < (1 << 14));
+    int n   = (nx > ny) ? ny : nx;
+    int p   = 1;
+    int p2;
+
+    while (p <= n)
+        p <<= 1;
+
+    p >>= 1;
+    p2  = p;
+    p >>= 1;
+
+    while (p >= 1) {
+        uint16_t *py = in;
+        uint16_t *ey = in + oy * (ny - p2);
+        uint16_t i00, i01, i10, i11;
+        int oy1 = oy * p;
+        int oy2 = oy * p2;
+        int ox1 = ox * p;
+        int ox2 = ox * p2;
+
+        for (; py <= ey; py += oy2) {
+            uint16_t *px = py;
+            uint16_t *ex = py + ox * (nx - p2);
+
+            for (; px <= ex; px += ox2) {
+                uint16_t *p01 = px + ox1;
+                uint16_t *p10 = px + oy1;
+                uint16_t *p11 = p10 + ox1;
+
+                if (w14) {
+                    wdec14(*px, *p10, &i00, &i10);
+                    wdec14(*p01, *p11, &i01, &i11);
+                    wdec14(i00, i01, px, p01);
+                    wdec14(i10, i11, p10, p11);
+                } else {
+                    wdec16(*px, *p10, &i00, &i10);
+                    wdec16(*p01, *p11, &i01, &i11);
+                    wdec16(i00, i01, px, p01);
+                    wdec16(i10, i11, p10, p11);
+                }
+            }
+
+            if (nx & p) {
+                uint16_t *p10 = px + oy1;
+
+                if (w14)
+                    wdec14(*px, *p10, &i00, p10);
+                else
+                    wdec16(*px, *p10, &i00, p10);
+
+                *px = i00;
+            }
+        }
+
+        if (ny & p) {
+            uint16_t *px = py;
+            uint16_t *ex = py + ox * (nx - p2);
+
+            for (; px <= ex; px += ox2) {
+                uint16_t *p01 = px + ox1;
+
+                if (w14)
+                    wdec14(*px, *p01, &i00, p01);
+                else
+                    wdec16(*px, *p01, &i00, p01);
+
+                *px = i00;
+            }
+        }
+
+        p2  = p;
+        p >>= 1;
+    }
+}
+
+static int piz_uncompress(EXRContext *s, const uint8_t *src, int ssize,
+                          int dsize, EXRThreadData *td)
+{
+    GetByteContext gb;
+    uint16_t maxval, min_non_zero, max_non_zero;
+    uint16_t *ptr;
+    uint16_t *tmp = (uint16_t *)td->tmp;
+    uint8_t *out;
+    int ret, i, j;
+
+    if (!td->bitmap)
+        td->bitmap = av_malloc(BITMAP_SIZE);
+    if (!td->lut)
+        td->lut = av_malloc(1 << 17);
+    if (!td->bitmap || !td->lut) {
+        av_free(td->bitmap);
+        av_free(td->lut);
+        return AVERROR(ENOMEM);
+    }
+
+    bytestream2_init(&gb, src, ssize);
+    min_non_zero = bytestream2_get_le16(&gb);
+    max_non_zero = bytestream2_get_le16(&gb);
+
+    if (max_non_zero >= BITMAP_SIZE)
+        return AVERROR_INVALIDDATA;
+
+    memset(td->bitmap, 0, FFMIN(min_non_zero, BITMAP_SIZE));
+    if (min_non_zero <= max_non_zero)
+        bytestream2_get_buffer(&gb, td->bitmap + min_non_zero,
+                               max_non_zero - min_non_zero + 1);
+    memset(td->bitmap + max_non_zero, 0, BITMAP_SIZE - max_non_zero);
+
+    maxval = reverse_lut(td->bitmap, td->lut);
+
+    ret = huf_uncompress(&gb, tmp, dsize / sizeof(uint16_t));
+    if (ret)
+        return ret;
+
+    ptr = tmp;
+    for (i = 0; i < s->nb_channels; i++) {
+        EXRChannel *channel = &s->channels[i];
+        int size = channel->pixel_type;
+
+        for (j = 0; j < size; j++)
+            wav_decode(ptr + j, s->xdelta, size, s->ysize,
+                       s->xdelta * size, maxval);
+        ptr += s->xdelta * s->ysize * size;
+    }
+
+    apply_lut(td->lut, tmp, dsize / sizeof(uint16_t));
+
+    out = td->uncompressed_data;
+    for (i = 0; i < s->ysize; i++)
+        for (j = 0; j < s->nb_channels; j++) {
+            uint16_t *in = tmp + j * s->xdelta * s->ysize + i * s->xdelta;
+            memcpy(out, in, s->xdelta * 2);
+            out += s->xdelta * 2;
+        }
+
+    return 0;
+}
+
+static int pxr24_uncompress(EXRContext *s, const uint8_t *src,
+                            int compressed_size, int uncompressed_size,
+                            EXRThreadData *td)
+{
+    unsigned long dest_len = uncompressed_size;
+    const uint8_t *in = td->tmp;
+    uint8_t *out;
+    int c, i, j;
+
+    if (uncompress(td->tmp, &dest_len, src, compressed_size) != Z_OK ||
+        dest_len != uncompressed_size)
+        return AVERROR_INVALIDDATA;
+
+    out = td->uncompressed_data;
+    for (i = 0; i < s->ysize; i++)
+        for (c = 0; c < s->nb_channels; c++) {
+            EXRChannel *channel = &s->channels[c];
+            const uint8_t *ptr[4];
+            uint32_t pixel = 0;
+
+            switch (channel->pixel_type) {
+            case EXR_FLOAT:
+                ptr[0] = in;
+                ptr[1] = ptr[0] + s->xdelta;
+                ptr[2] = ptr[1] + s->xdelta;
+                in     = ptr[2] + s->xdelta;
+
+                for (j = 0; j < s->xdelta; ++j) {
+                    uint32_t diff = (*(ptr[0]++) << 24) |
+                                    (*(ptr[1]++) << 16) |
+                                    (*(ptr[2]++) << 8);
+                    pixel += diff;
+                    bytestream_put_le32(&out, pixel);
+                }
+                break;
+            case EXR_HALF:
+                ptr[0] = in;
+                ptr[1] = ptr[0] + s->xdelta;
+                in     = ptr[1] + s->xdelta;
+                for (j = 0; j < s->xdelta; j++) {
+                    uint32_t diff = (*(ptr[0]++) << 8) | *(ptr[1]++);
+
+                    pixel += diff;
+                    bytestream_put_le16(&out, pixel);
+                }
+                break;
+            default:
+                return AVERROR_INVALIDDATA;
+            }
+        }
+
+    return 0;
+}
+
+static int decode_block(AVCodecContext *avctx, void *tdata,
+                        int jobnr, int threadnr)
+{
+    EXRContext *s = avctx->priv_data;
+    AVFrame *const p = s->picture;
+    EXRThreadData *td = &s->thread_data[threadnr];
+    const uint8_t *channel_buffer[4] = { 0 };
+    const uint8_t *buf = s->buf;
+    uint64_t line_offset, uncompressed_size;
+    uint32_t xdelta = s->xdelta;
+    uint16_t *ptr_x;
+    uint8_t *ptr;
+    uint32_t data_size, line;
+    const uint8_t *src;
+    int axmax = (avctx->width - (s->xmax + 1)) * 2 * s->desc->nb_components;
+    int bxmin = s->xmin * 2 * s->desc->nb_components;
+    int i, x, buf_size = s->buf_size;
+    int ret;
+
+    line_offset = AV_RL64(s->gb.buffer + jobnr * 8);
+    // Check if the buffer has the required bytes needed from the offset
+    if (line_offset > buf_size - 8)
+        return AVERROR_INVALIDDATA;
+
+    src  = buf + line_offset + 8;
+    line = AV_RL32(src - 8);
+    if (line < s->ymin || line > s->ymax)
+        return AVERROR_INVALIDDATA;
+
+    data_size = AV_RL32(src - 4);
+    if (data_size <= 0 || data_size > buf_size)
+        return AVERROR_INVALIDDATA;
+
+    s->ysize          = FFMIN(s->scan_lines_per_block, s->ymax - line + 1);
+    uncompressed_size = s->scan_line_size * s->ysize;
+    if ((s->compression == EXR_RAW && (data_size != uncompressed_size ||
+                                 line_offset > buf_size - uncompressed_size)) ||
+        (s->compression != EXR_RAW && (data_size > uncompressed_size ||
+                                 line_offset > buf_size - data_size))) {
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (data_size < uncompressed_size) {
+        av_fast_padded_malloc(&td->uncompressed_data,
+                              &td->uncompressed_size, uncompressed_size);
+        av_fast_padded_malloc(&td->tmp, &td->tmp_size, uncompressed_size);
+        if (!td->uncompressed_data || !td->tmp)
+            return AVERROR(ENOMEM);
+
+        ret = AVERROR_INVALIDDATA;
+        switch (s->compression) {
+        case EXR_ZIP1:
+        case EXR_ZIP16:
+            ret = zip_uncompress(src, data_size, uncompressed_size, td);
+            break;
+        case EXR_PIZ:
+            ret = piz_uncompress(s, src, data_size, uncompressed_size, td);
+            break;
+        case EXR_PXR24:
+            ret = pxr24_uncompress(s, src, data_size, uncompressed_size, td);
+            break;
+        case EXR_RLE:
+            ret = rle_uncompress(src, data_size, uncompressed_size, td);
+        }
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "decode_block() failed.\n");
+            return ret;
+        }
+        src = td->uncompressed_data;
+    }
+
+    channel_buffer[0] = src + xdelta * s->channel_offsets[0];
+    channel_buffer[1] = src + xdelta * s->channel_offsets[1];
+    channel_buffer[2] = src + xdelta * s->channel_offsets[2];
+    if (s->channel_offsets[3] >= 0)
+        channel_buffer[3] = src + xdelta * s->channel_offsets[3];
+
+    ptr = p->data[0] + line * p->linesize[0];
+    for (i = 0;
+         i < s->scan_lines_per_block && line + i <= s->ymax;
+         i++, ptr += p->linesize[0]) {
+        const uint8_t *r, *g, *b, *a;
+
+        r = channel_buffer[0];
+        g = channel_buffer[1];
+        b = channel_buffer[2];
+        if (channel_buffer[3])
+            a = channel_buffer[3];
+
+        ptr_x = (uint16_t *) ptr;
+
+        // Zero out the start if xmin is not 0
+        memset(ptr_x, 0, bxmin);
+        ptr_x += s->xmin * s->desc->nb_components;
+        if (s->pixel_type == EXR_FLOAT) {
+            // 32-bit
+            for (x = 0; x < xdelta; x++) {
+                *ptr_x++ = exr_flt2uint(bytestream_get_le32(&r));
+                *ptr_x++ = exr_flt2uint(bytestream_get_le32(&g));
+                *ptr_x++ = exr_flt2uint(bytestream_get_le32(&b));
+                if (channel_buffer[3])
+                    *ptr_x++ = exr_flt2uint(bytestream_get_le32(&a));
+            }
+        } else {
+            // 16-bit
+            for (x = 0; x < xdelta; x++) {
+                *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&r));
+                *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&g));
+                *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&b));
+                if (channel_buffer[3])
+                    *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&a));
+            }
+        }
+
+        // Zero out the end if xmax+1 is not w
+        memset(ptr_x, 0, axmax);
+
+        channel_buffer[0] += s->scan_line_size;
+        channel_buffer[1] += s->scan_line_size;
+        channel_buffer[2] += s->scan_line_size;
+        if (channel_buffer[3])
+            channel_buffer[3] += s->scan_line_size;
+    }
+
+    return 0;
+}
+
+/**
+ * Check if the variable name corresponds to its data type.
+ *
+ * @param s              the EXRContext
+ * @param value_name     name of the variable to check
+ * @param value_type     type of the variable to check
+ * @param minimum_length minimum length of the variable data
+ *
+ * @return bytes to read containing variable data
+ *         -1 if variable is not found
+ *         0 if buffer ended prematurely
+ */
+static int check_header_variable(EXRContext *s,
+                                 const char *value_name,
+                                 const char *value_type,
+                                 unsigned int minimum_length)
+{
+    int var_size = -1;
+
+    if (bytestream2_get_bytes_left(&s->gb) >= minimum_length &&
+        !strcmp(s->gb.buffer, value_name)) {
+        // found value_name, jump to value_type (null terminated strings)
+        s->gb.buffer += strlen(value_name) + 1;
+        if (!strcmp(s->gb.buffer, value_type)) {
+            s->gb.buffer += strlen(value_type) + 1;
+            var_size = bytestream2_get_le32(&s->gb);
+            // don't go read past boundaries
+            if (var_size > bytestream2_get_bytes_left(&s->gb))
+                var_size = 0;
+        } else {
+            // value_type not found, reset the buffer
+            s->gb.buffer -= strlen(value_name) + 1;
+            av_log(s->avctx, AV_LOG_WARNING,
+                   "Unknown data type %s for header variable %s.\n",
+                   value_type, value_name);
+        }
+    }
+
+    return var_size;
+}
+
+static int decode_header(EXRContext *s)
+{
+    int current_channel_offset = 0;
+    int magic_number, version, flags, i;
+
+    if (bytestream2_get_bytes_left(&s->gb) < 10) {
+        av_log(s->avctx, AV_LOG_ERROR, "Header too short to parse.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    magic_number = bytestream2_get_le32(&s->gb);
+    if (magic_number != 20000630) {
+        /* As per documentation of OpenEXR, it is supposed to be
+         * int 20000630 little-endian */
+        av_log(s->avctx, AV_LOG_ERROR, "Wrong magic number %d.\n", magic_number);
+        return AVERROR_INVALIDDATA;
+    }
+
+    version = bytestream2_get_byte(&s->gb);
+    if (version != 2) {
+        avpriv_report_missing_feature(s->avctx, "Version %d", version);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    flags = bytestream2_get_le24(&s->gb);
+    if (flags & 0x02) {
+        avpriv_report_missing_feature(s->avctx, "Tile support");
+        return AVERROR_PATCHWELCOME;
+    }
+
+    // Parse the header
+    while (bytestream2_get_bytes_left(&s->gb) > 0 && *s->gb.buffer) {
+        int var_size;
+        if ((var_size = check_header_variable(s, "channels",
+                                              "chlist", 38)) >= 0) {
+            GetByteContext ch_gb;
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            bytestream2_init(&ch_gb, s->gb.buffer, var_size);
+
+            while (bytestream2_get_bytes_left(&ch_gb) >= 19) {
+                EXRChannel *channel;
+                enum ExrPixelType current_pixel_type;
+                int channel_index = -1;
+                int xsub, ysub;
+
+                if (strcmp(s->layer, "") != 0) {
+                    if (strncmp(ch_gb.buffer, s->layer, strlen(s->layer)) == 0) {
+                        ch_gb.buffer += strlen(s->layer);
+                        if (*ch_gb.buffer == '.')
+                            ch_gb.buffer++;         /* skip dot if not given */
+                        av_log(s->avctx, AV_LOG_INFO,
+                               "Layer %s.%s matched.\n", s->layer, ch_gb.buffer);
+                    }
+                }
+
+                if (!strcmp(ch_gb.buffer, "R") ||
+                    !strcmp(ch_gb.buffer, "X") ||
+                    !strcmp(ch_gb.buffer, "U"))
+                    channel_index = 0;
+                else if (!strcmp(ch_gb.buffer, "G") ||
+                         !strcmp(ch_gb.buffer, "Y") ||
+                         !strcmp(ch_gb.buffer, "V"))
+                    channel_index = 1;
+                else if (!strcmp(ch_gb.buffer, "B") ||
+                         !strcmp(ch_gb.buffer, "Z") ||
+                         !strcmp(ch_gb.buffer, "W"))
+                    channel_index = 2;
+                else if (!strcmp(ch_gb.buffer, "A"))
+                    channel_index = 3;
+                else
+                    av_log(s->avctx, AV_LOG_WARNING,
+                           "Unsupported channel %.256s.\n", ch_gb.buffer);
+
+                /* skip until you get a 0 */
+                while (bytestream2_get_bytes_left(&ch_gb) > 0 &&
+                       bytestream2_get_byte(&ch_gb))
+                    continue;
+
+                if (bytestream2_get_bytes_left(&ch_gb) < 4) {
+                    av_log(s->avctx, AV_LOG_ERROR, "Incomplete header.\n");
+                    return AVERROR_INVALIDDATA;
+                }
+
+                current_pixel_type = bytestream2_get_le32(&ch_gb);
+                if (current_pixel_type >= EXR_UNKNOWN) {
+                    avpriv_report_missing_feature(s->avctx,
+                                                  "Pixel type %d.\n",
+                                                  current_pixel_type);
+                    return AVERROR_PATCHWELCOME;
+                }
+
+                bytestream2_skip(&ch_gb, 4);
+                xsub = bytestream2_get_le32(&ch_gb);
+                ysub = bytestream2_get_le32(&ch_gb);
+                if (xsub != 1 || ysub != 1) {
+                    avpriv_report_missing_feature(s->avctx,
+                                                  "Subsampling %dx%d",
+                                                  xsub, ysub);
+                    return AVERROR_PATCHWELCOME;
+                }
+
+                if (channel_index >= 0) {
+                    if (s->pixel_type != EXR_UNKNOWN &&
+                        s->pixel_type != current_pixel_type) {
+                        av_log(s->avctx, AV_LOG_ERROR,
+                               "RGB channels not of the same depth.\n");
+                        return AVERROR_INVALIDDATA;
+                    }
+                    s->pixel_type                     = current_pixel_type;
+                    s->channel_offsets[channel_index] = current_channel_offset;
+                }
+
+                s->channels = av_realloc(s->channels,
+                                         ++s->nb_channels * sizeof(EXRChannel));
+                if (!s->channels)
+                    return AVERROR(ENOMEM);
+                channel             = &s->channels[s->nb_channels - 1];
+                channel->pixel_type = current_pixel_type;
+                channel->xsub       = xsub;
+                channel->ysub       = ysub;
+
+                current_channel_offset += 1 << current_pixel_type;
+            }
+
+            /* Check if all channels are set with an offset or if the channels
+             * are causing an overflow  */
+            if (FFMIN3(s->channel_offsets[0],
+                       s->channel_offsets[1],
+                       s->channel_offsets[2]) < 0) {
+                if (s->channel_offsets[0] < 0)
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing red channel.\n");
+                if (s->channel_offsets[1] < 0)
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing green channel.\n");
+                if (s->channel_offsets[2] < 0)
+                    av_log(s->avctx, AV_LOG_ERROR, "Missing blue channel.\n");
+                return AVERROR_INVALIDDATA;
+            }
+
+            // skip one last byte and update main gb
+            s->gb.buffer = ch_gb.buffer + 1;
+            continue;
+        } else if ((var_size = check_header_variable(s, "dataWindow", "box2i",
+                                                     31)) >= 0) {
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            s->xmin   = bytestream2_get_le32(&s->gb);
+            s->ymin   = bytestream2_get_le32(&s->gb);
+            s->xmax   = bytestream2_get_le32(&s->gb);
+            s->ymax   = bytestream2_get_le32(&s->gb);
+            s->xdelta = (s->xmax - s->xmin) + 1;
+            s->ydelta = (s->ymax - s->ymin) + 1;
+
+            continue;
+        } else if ((var_size = check_header_variable(s, "displayWindow",
+                                                     "box2i", 34)) >= 0) {
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            bytestream2_skip(&s->gb, 8);
+            s->w = bytestream2_get_le32(&s->gb) + 1;
+            s->h = bytestream2_get_le32(&s->gb) + 1;
+
+            continue;
+        } else if ((var_size = check_header_variable(s, "lineOrder",
+                                                     "lineOrder", 25)) >= 0) {
+            int line_order;
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            line_order = bytestream2_get_byte(&s->gb);
+            av_log(s->avctx, AV_LOG_DEBUG, "line order: %d.\n", line_order);
+            if (line_order > 2) {
+                av_log(s->avctx, AV_LOG_ERROR, "Unknown line order.\n");
+                return AVERROR_INVALIDDATA;
+            }
+
+            continue;
+        } else if ((var_size = check_header_variable(s, "pixelAspectRatio",
+                                                     "float", 31)) >= 0) {
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            s->avctx->sample_aspect_ratio =
+                av_d2q(av_int2float(bytestream2_get_le32(&s->gb)), 255);
+
+            continue;
+        } else if ((var_size = check_header_variable(s, "compression",
+                                                     "compression", 29)) >= 0) {
+            if (!var_size)
+                return AVERROR_INVALIDDATA;
+
+            if (s->compression == EXR_UNKN)
+                s->compression = bytestream2_get_byte(&s->gb);
+            else
+                av_log(s->avctx, AV_LOG_WARNING,
+                       "Found more than one compression attribute.\n");
+
+            continue;
+        }
+
+        // Check if there are enough bytes for a header
+        if (bytestream2_get_bytes_left(&s->gb) <= 9) {
+            av_log(s->avctx, AV_LOG_ERROR, "Incomplete header\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        // Process unknown variables
+        for (i = 0; i < 2; i++) // value_name and value_type
+            while (bytestream2_get_byte(&s->gb) != 0);
+
+        // Skip variable length
+        bytestream2_skip(&s->gb, bytestream2_get_le32(&s->gb));
+    }
+
+    if (s->compression == EXR_UNKN) {
+        av_log(s->avctx, AV_LOG_ERROR, "Missing compression attribute.\n");
+        return AVERROR_INVALIDDATA;
+    }
+    s->scan_line_size = s->xdelta * current_channel_offset;
+
+    if (bytestream2_get_bytes_left(&s->gb) <= 0) {
+        av_log(s->avctx, AV_LOG_ERROR, "Incomplete frame.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    // aaand we are done
+    bytestream2_skip(&s->gb, 1);
+    return 0;
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data,
+                        int *got_frame, AVPacket *avpkt)
+{
+    EXRContext *s = avctx->priv_data;
+    ThreadFrame frame = { .f = data };
+    AVFrame *picture = data;
+    uint8_t *ptr;
+
+    int y, ret;
+    int out_line_size;
+    int scan_line_blocks;
+
+    bytestream2_init(&s->gb, avpkt->data, avpkt->size);
+
+    if ((ret = decode_header(s)) < 0)
+        return ret;
+
+    switch (s->pixel_type) {
+    case EXR_FLOAT:
+    case EXR_HALF:
+        if (s->channel_offsets[3] >= 0)
+            avctx->pix_fmt = AV_PIX_FMT_RGBA64;
+        else
+            avctx->pix_fmt = AV_PIX_FMT_RGB48;
+        break;
+    case EXR_UINT:
+        avpriv_request_sample(avctx, "32-bit unsigned int");
+        return AVERROR_PATCHWELCOME;
+    default:
+        av_log(avctx, AV_LOG_ERROR, "Missing channel list.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    switch (s->compression) {
+    case EXR_RAW:
+    case EXR_RLE:
+    case EXR_ZIP1:
+        s->scan_lines_per_block = 1;
+        break;
+    case EXR_PXR24:
+    case EXR_ZIP16:
+        s->scan_lines_per_block = 16;
+        break;
+    case EXR_PIZ:
+        s->scan_lines_per_block = 32;
+        break;
+    default:
+        avpriv_report_missing_feature(avctx, "Compression %d", s->compression);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    /* Verify the xmin, xmax, ymin, ymax and xdelta before setting
+     * the actual image size. */
+    if (s->xmin > s->xmax                  ||
+        s->ymin > s->ymax                  ||
+        s->xdelta != s->xmax - s->xmin + 1 ||
+        s->xmax >= s->w                    ||
+        s->ymax >= s->h) {
+        av_log(avctx, AV_LOG_ERROR, "Wrong or missing size information.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if ((ret = ff_set_dimensions(avctx, s->w, s->h)) < 0)
+        return ret;
+
+    s->desc          = av_pix_fmt_desc_get(avctx->pix_fmt);
+    if (!s->desc)
+        return AVERROR_INVALIDDATA;
+    out_line_size    = avctx->width * 2 * s->desc->nb_components;
+    scan_line_blocks = (s->ydelta + s->scan_lines_per_block - 1) /
+                       s->scan_lines_per_block;
+
+    if ((ret = ff_thread_get_buffer(avctx, &frame, 0)) < 0)
+        return ret;
+
+    if (bytestream2_get_bytes_left(&s->gb) < scan_line_blocks * 8)
+        return AVERROR_INVALIDDATA;
+
+    // save pointer we are going to use in decode_block
+    s->buf      = avpkt->data;
+    s->buf_size = avpkt->size;
+    ptr         = picture->data[0];
+
+    // Zero out the start if ymin is not 0
+    for (y = 0; y < s->ymin; y++) {
+        memset(ptr, 0, out_line_size);
+        ptr += picture->linesize[0];
+    }
+
+    s->picture = picture;
+    avctx->execute2(avctx, decode_block, s->thread_data, NULL, scan_line_blocks);
+
+    // Zero out the end if ymax+1 is not h
+    for (y = s->ymax + 1; y < avctx->height; y++) {
+        memset(ptr, 0, out_line_size);
+        ptr += picture->linesize[0];
+    }
+
+    picture->pict_type = AV_PICTURE_TYPE_I;
+    *got_frame = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    EXRContext *s = avctx->priv_data;
+
+    s->avctx              = avctx;
+    s->xmin               = ~0;
+    s->xmax               = ~0;
+    s->ymin               = ~0;
+    s->ymax               = ~0;
+    s->xdelta             = ~0;
+    s->ydelta             = ~0;
+    s->channel_offsets[0] = -1;
+    s->channel_offsets[1] = -1;
+    s->channel_offsets[2] = -1;
+    s->channel_offsets[3] = -1;
+    s->pixel_type         = EXR_UNKNOWN;
+    s->compression        = EXR_UNKN;
+    s->nb_channels        = 0;
+    s->w                  = 0;
+    s->h                  = 0;
+
+    // allocate thread data, used for non EXR_RAW compreesion types
+    s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
+    if (!s->thread_data)
+        return AVERROR_INVALIDDATA;
+
+    return 0;
+}
+
+static int decode_init_thread_copy(AVCodecContext *avctx)
+{    EXRContext *s = avctx->priv_data;
+
+    // allocate thread data, used for non EXR_RAW compreesion types
+    s->thread_data = av_mallocz_array(avctx->thread_count, sizeof(EXRThreadData));
+    if (!s->thread_data)
+        return AVERROR_INVALIDDATA;
+
+    return 0;
+}
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+    EXRContext *s = avctx->priv_data;
+    int i;
+    for (i = 0; i < avctx->thread_count; i++) {
+        EXRThreadData *td = &s->thread_data[i];
+        av_freep(&td->uncompressed_data);
+        av_freep(&td->tmp);
+        av_freep(&td->bitmap);
+        av_freep(&td->lut);
+    }
+
+    av_freep(&s->thread_data);
+    av_freep(&s->channels);
+
+    return 0;
+}
+
+#define OFFSET(x) offsetof(EXRContext, x)
+#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
+static const AVOption options[] = {
+    { "layer", "Set the decoding layer", OFFSET(layer),
+        AV_OPT_TYPE_STRING, { .str = "" }, 0, 0, VD },
+    { NULL },
+};
+
+static const AVClass exr_class = {
+    .class_name = "EXR",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_exr_decoder = {
+    .name             = "exr",
+    .long_name        = NULL_IF_CONFIG_SMALL("OpenEXR image"),
+    .type             = AVMEDIA_TYPE_VIDEO,
+    .id               = AV_CODEC_ID_EXR,
+    .priv_data_size   = sizeof(EXRContext),
+    .init             = decode_init,
+    .init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
+    .close            = decode_end,
+    .decode           = decode_frame,
+    .capabilities     = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS |
+                        CODEC_CAP_SLICE_THREADS,
+    .priv_class       = &exr_class,
+};