Canopus HQX decoder

Based on work by Kostya Shishkov <kostya.shishkov@gmail.com>.

1 files changed, 645 insertions, 0 deletions

diff --git a/libavcodec/hqx.c b/libavcodec/hqx.c
new file mode 100644
index 0000000000..3feb2871d3
--- /dev/null
+++ b/libavcodec/hqx.c
@@ -0,0 +1,645 @@
+/*
+ * Canopus HQX decoder
+ *
+ * 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
+ */
+
+#include <inttypes.h>
+
+#include "libavutil/imgutils.h"
+#include "libavutil/intreadwrite.h"
+
+#include "avcodec.h"
+#include "get_bits.h"
+#include "internal.h"
+
+#include "hqx.h"
+
+/* HQX has four modes - 422, 444, 422alpha and 444alpha - all 12-bit */
+enum HQXFormat {
+    HQX_422 = 0,
+    HQX_444,
+    HQX_422A,
+    HQX_444A,
+};
+
+#define HQX_HEADER_SIZE 59
+
+typedef int (*mb_decode_func)(HQXContext *ctx, AVFrame *pic,
+                              GetBitContext *gb, int x, int y);
+
+/* macroblock selects a group of 4 possible quants and
+ * a block can use any of those four quantisers
+ * one column is powers of 2, the other one is powers of 2 * 3,
+ * then there is the special one, powers of 2 * 5 */
+static const int hqx_quants[16][4] = {
+    {  0x1,   0x2,   0x4,   0x8 }, {  0x1,  0x3,   0x6,   0xC },
+    {  0x2,   0x4,   0x8,  0x10 }, {  0x3,  0x6,   0xC,  0x18 },
+    {  0x4,   0x8,  0x10,  0x20 }, {  0x6,  0xC,  0x18,  0x30 },
+    {  0x8,  0x10,  0x20,  0x40 },
+                      { 0xA, 0x14, 0x28, 0x50 },
+                                   {  0xC, 0x18,  0x30,  0x60 },
+    { 0x10,  0x20,  0x40,  0x80 }, { 0x18, 0x30,  0x60,  0xC0 },
+    { 0x20,  0x40,  0x80, 0x100 }, { 0x30, 0x60,  0xC0, 0x180 },
+    { 0x40,  0x80, 0x100, 0x200 }, { 0x60, 0xC0, 0x180, 0x300 },
+    { 0x80, 0x100, 0x200, 0x400 }
+};
+
+static const uint8_t hqx_quant_luma[64] = {
+    16,  16,  16,  19,  19,  19,  42,  44,
+    16,  16,  19,  19,  19,  38,  43,  45,
+    16,  19,  19,  19,  40,  41,  45,  48,
+    19,  19,  19,  40,  41,  42,  46,  49,
+    19,  19,  40,  41,  42,  43,  48, 101,
+    19,  38,  41,  42,  43,  44,  98, 104,
+    42,  43,  45,  46,  48,  98, 109, 116,
+    44,  45,  48,  49, 101, 104, 116, 123,
+};
+
+static const uint8_t hqx_quant_chroma[64] = {
+    16,  16,  19,  25,  26,  26,  42,  44,
+    16,  19,  25,  25,  26,  38,  43,  91,
+    19,  25,  26,  27,  40,  41,  91,  96,
+    25,  25,  27,  40,  41,  84,  93, 197,
+    26,  26,  40,  41,  84,  86, 191, 203,
+    26,  38,  41,  84,  86, 177, 197, 209,
+    42,  43,  91,  93, 191, 197, 219, 232,
+    44,  91,  96, 197, 203, 209, 232, 246,
+};
+
+static inline void idct_col(int16_t *blk, const uint8_t *quant)
+{
+    int t0, t1, t2, t3, t4, t5, t6, t7, t8, t9, tA, tB, tC, tD, tE, tF;
+    int t10, t11, t12, t13;
+    int s0, s1, s2, s3, s4, s5, s6, s7;
+
+    s0 = (int) blk[0 * 8] * quant[0 * 8];
+    s1 = (int) blk[1 * 8] * quant[1 * 8];
+    s2 = (int) blk[2 * 8] * quant[2 * 8];
+    s3 = (int) blk[3 * 8] * quant[3 * 8];
+    s4 = (int) blk[4 * 8] * quant[4 * 8];
+    s5 = (int) blk[5 * 8] * quant[5 * 8];
+    s6 = (int) blk[6 * 8] * quant[6 * 8];
+    s7 = (int) blk[7 * 8] * quant[7 * 8];
+
+    t0  =  (s3 * 19266 + s5 * 12873) >> 15;
+    t1  =  (s5 * 19266 - s3 * 12873) >> 15;
+    t2  = ((s7 * 4520  + s1 * 22725) >> 15) - t0;
+    t3  = ((s1 * 4520  - s7 * 22725) >> 15) - t1;
+    t4  = t0 * 2 + t2;
+    t5  = t1 * 2 + t3;
+    t6  = t2 - t3;
+    t7  = t3 * 2 + t6;
+    t8  = (t6 * 11585) >> 14;
+    t9  = (t7 * 11585) >> 14;
+    tA  = (s2 * 8867 - s6 * 21407) >> 14;
+    tB  = (s6 * 8867 + s2 * 21407) >> 14;
+    tC  = (s0 >> 1) - (s4 >> 1);
+    tD  = (s4 >> 1) * 2 + tC;
+    tE  = tC - (tA >> 1);
+    tF  = tD - (tB >> 1);
+    t10 = tF - t5;
+    t11 = tE - t8;
+    t12 = tE + (tA >> 1) * 2 - t9;
+    t13 = tF + (tB >> 1) * 2 - t4;
+
+    blk[0 * 8] = t13 + t4 * 2;
+    blk[1 * 8] = t12 + t9 * 2;
+    blk[2 * 8] = t11 + t8 * 2;
+    blk[3 * 8] = t10 + t5 * 2;
+    blk[4 * 8] = t10;
+    blk[5 * 8] = t11;
+    blk[6 * 8] = t12;
+    blk[7 * 8] = t13;
+}
+
+static inline void idct_row(int16_t *blk)
+{
+    int t0, t1, t2, t3, t4, t5, t6, t7, t8, t9, tA, tB, tC, tD, tE, tF;
+    int t10, t11, t12, t13;
+
+    t0  =  (blk[3] * 19266 + blk[5] * 12873) >> 14;
+    t1  =  (blk[5] * 19266 - blk[3] * 12873) >> 14;
+    t2  = ((blk[7] * 4520  + blk[1] * 22725) >> 14) - t0;
+    t3  = ((blk[1] * 4520  - blk[7] * 22725) >> 14) - t1;
+    t4  = t0 * 2 + t2;
+    t5  = t1 * 2 + t3;
+    t6  = t2 - t3;
+    t7  = t3 * 2 + t6;
+    t8  = (t6 * 11585) >> 14;
+    t9  = (t7 * 11585) >> 14;
+    tA  = (blk[2] * 8867 - blk[6] * 21407) >> 14;
+    tB  = (blk[6] * 8867 + blk[2] * 21407) >> 14;
+    tC  = blk[0] - blk[4];
+    tD  = blk[4] * 2 + tC;
+    tE  = tC - tA;
+    tF  = tD - tB;
+    t10 = tF - t5;
+    t11 = tE - t8;
+    t12 = tE + tA * 2 - t9;
+    t13 = tF + tB * 2 - t4;
+
+    blk[0] = (t13 + t4 * 2 + 4) >> 3;
+    blk[1] = (t12 + t9 * 2 + 4) >> 3;
+    blk[2] = (t11 + t8 * 2 + 4) >> 3;
+    blk[3] = (t10 + t5 * 2 + 4) >> 3;
+    blk[4] = (t10          + 4) >> 3;
+    blk[5] = (t11          + 4) >> 3;
+    blk[6] = (t12          + 4) >> 3;
+    blk[7] = (t13          + 4) >> 3;
+}
+
+static void hqx_idct(int16_t *block, const uint8_t *quant)
+{
+    int i;
+
+    for (i = 0; i < 8; i++)
+        idct_col(block + i, quant + i);
+    for (i = 0; i < 8; i++)
+        idct_row(block + i * 8);
+}
+
+static void hqx_idct_put(uint16_t *dst, ptrdiff_t stride,
+                         int16_t *block, const uint8_t *quant)
+{
+    int i, j;
+
+    hqx_idct(block, quant);
+
+    for (i = 0; i < 8; i++) {
+        for (j = 0; j < 8; j++) {
+            int v = av_clip(block[j + i * 8] + 0x800, 0, 0x1000);
+            dst[j] = (v << 4) | (v >> 8);
+        }
+        dst += stride >> 1;
+    }
+}
+
+static inline void put_blocks(AVFrame *pic, int plane,
+                              int x, int y, int ilace,
+                              int16_t *block0, int16_t *block1,
+                              const uint8_t *quant)
+{
+    int fields = ilace ? 2 : 1;
+    int lsize = pic->linesize[plane];
+    uint8_t *p = pic->data[plane] + x * 2;
+
+    hqx_idct_put((uint16_t *)(p + y * lsize), lsize * fields, block0, quant);
+    hqx_idct_put((uint16_t *)(p + (y + (ilace ? 1 : 8)) * lsize),
+                 lsize * fields, block1, quant);
+}
+
+static inline void hqx_get_ac(GetBitContext *gb, const HQXAC *ac,
+                              int *run, int *lev)
+{
+    int val;
+
+    val = show_bits(gb, ac->lut_bits);
+    if (ac->lut[val].bits == -1) {
+        GetBitContext gb2 = *gb;
+        skip_bits(&gb2, ac->lut_bits);
+        val = ac->lut[val].lev + show_bits(&gb2, ac->extra_bits);
+    }
+    *run = ac->lut[val].run;
+    *lev = ac->lut[val].lev;
+    skip_bits(gb, ac->lut[val].bits);
+}
+
+static int decode_block(GetBitContext *gb, VLC *vlc,
+                        const int *quants, int dcb,
+                        int16_t block[64], int *last_dc)
+{
+    int q, dc;
+    int ac_idx;
+    int run, lev, pos = 1;
+
+    memset(block, 0, 64 * sizeof(*block));
+    dc = get_vlc2(gb, vlc->table, HQX_DC_VLC_BITS, 2);
+    if (dc < 0)
+        return AVERROR_INVALIDDATA;
+    *last_dc += dc;
+
+    block[0] = sign_extend(*last_dc << (12 - dcb), 12);
+
+    q = quants[get_bits(gb, 2)];
+    if (q >= 128)
+        ac_idx = HQX_AC_Q128;
+    else if (q >= 64)
+        ac_idx = HQX_AC_Q64;
+    else if (q >= 32)
+        ac_idx = HQX_AC_Q32;
+    else if (q >= 16)
+        ac_idx = HQX_AC_Q16;
+    else if (q >= 8)
+        ac_idx = HQX_AC_Q8;
+    else
+        ac_idx = HQX_AC_Q0;
+
+    do {
+        hqx_get_ac(gb, &ff_hqx_ac[ac_idx], &run, &lev);
+        pos += run;
+        if (pos >= 64)
+            break;
+        block[ff_zigzag_direct[pos++]] = lev * q;
+    } while (pos < 64);
+
+    return 0;
+}
+
+static int hqx_decode_422(HQXContext *ctx, AVFrame *pic,
+                          GetBitContext *gb, int x, int y)
+{
+    const int *quants;
+    int flag;
+    int last_dc;
+    int i, ret;
+
+    if (ctx->interlaced)
+        flag = get_bits1(gb);
+    else
+        flag = 0;
+
+    quants = hqx_quants[get_bits(gb, 4)];
+
+    for (i = 0; i < 8; i++) {
+        int vlc_index = ctx->dcb - 9;
+        if (i == 0 || i == 4 || i == 6)
+            last_dc = 0;
+        ret = decode_block(gb, &ctx->dc_vlc[vlc_index], quants,
+                           ctx->dcb, ctx->block[i], &last_dc);
+        if (ret < 0)
+            return ret;
+    }
+
+    put_blocks(pic, 0, x,      y, flag, ctx->block[0], ctx->block[2], hqx_quant_luma);
+    put_blocks(pic, 0, x + 8,  y, flag, ctx->block[1], ctx->block[3], hqx_quant_luma);
+    put_blocks(pic, 2, x >> 1, y, flag, ctx->block[4], ctx->block[5], hqx_quant_chroma);
+    put_blocks(pic, 1, x >> 1, y, flag, ctx->block[6], ctx->block[7], hqx_quant_chroma);
+
+    return 0;
+}
+
+static int hqx_decode_422a(HQXContext *ctx, AVFrame *pic,
+                           GetBitContext *gb, int x, int y)
+{
+    const int *quants;
+    int flag = 0;
+    int last_dc;
+    int i, ret;
+    int cbp;
+
+    cbp = get_vlc2(gb, ctx->cbp_vlc.table, ctx->cbp_vlc.bits, 1);
+
+    for (i = 0; i < 12; i++)
+        memset(ctx->block[i], 0, sizeof(**ctx->block) * 64);
+    for (i = 0; i < 12; i++)
+        ctx->block[i][0] = -0x800;
+    if (cbp) {
+        if (ctx->interlaced)
+            flag = get_bits1(gb);
+
+        quants = hqx_quants[get_bits(gb, 4)];
+
+        cbp |= cbp << 4; // alpha CBP
+        if (cbp & 0x3)   // chroma CBP - top
+            cbp |= 0x500;
+        if (cbp & 0xC)   // chroma CBP - bottom
+            cbp |= 0xA00;
+        for (i = 0; i < 12; i++) {
+            if (i == 0 || i == 4 || i == 8 || i == 10)
+                last_dc = 0;
+            if (cbp & (1 << i)) {
+                int vlc_index = ctx->dcb - 9;
+                ret = decode_block(gb, &ctx->dc_vlc[vlc_index], quants,
+                                   ctx->dcb, ctx->block[i], &last_dc);
+                if (ret < 0)
+                    return ret;
+            }
+        }
+    }
+
+    put_blocks(pic, 3, x,      y, flag, ctx->block[ 0], ctx->block[ 2], hqx_quant_luma);
+    put_blocks(pic, 3, x + 8,  y, flag, ctx->block[ 1], ctx->block[ 3], hqx_quant_luma);
+    put_blocks(pic, 0, x,      y, flag, ctx->block[ 4], ctx->block[ 6], hqx_quant_luma);
+    put_blocks(pic, 0, x + 8,  y, flag, ctx->block[ 5], ctx->block[ 7], hqx_quant_luma);
+    put_blocks(pic, 2, x >> 1, y, flag, ctx->block[ 8], ctx->block[ 9], hqx_quant_chroma);
+    put_blocks(pic, 1, x >> 1, y, flag, ctx->block[10], ctx->block[11], hqx_quant_chroma);
+
+    return 0;
+}
+
+static int hqx_decode_444(HQXContext *ctx, AVFrame *pic,
+                          GetBitContext *gb, int x, int y)
+{
+    const int *quants;
+    int flag;
+    int last_dc;
+    int i, ret;
+
+    if (ctx->interlaced)
+        flag = get_bits1(gb);
+    else
+        flag = 0;
+
+    quants = hqx_quants[get_bits(gb, 4)];
+
+    for (i = 0; i < 12; i++) {
+        int vlc_index = ctx->dcb - 9;
+        if (i == 0 || i == 4 || i == 8)
+            last_dc = 0;
+        ret = decode_block(gb, &ctx->dc_vlc[vlc_index], quants,
+                           ctx->dcb, ctx->block[i], &last_dc);
+        if (ret < 0)
+            return ret;
+    }
+
+    put_blocks(pic, 0, x,     y, flag, ctx->block[0], ctx->block[ 2], hqx_quant_luma);
+    put_blocks(pic, 0, x + 8, y, flag, ctx->block[1], ctx->block[ 3], hqx_quant_luma);
+    put_blocks(pic, 2, x,     y, flag, ctx->block[4], ctx->block[ 6], hqx_quant_chroma);
+    put_blocks(pic, 2, x + 8, y, flag, ctx->block[5], ctx->block[ 7], hqx_quant_chroma);
+    put_blocks(pic, 1, x,     y, flag, ctx->block[8], ctx->block[10], hqx_quant_chroma);
+    put_blocks(pic, 1, x + 8, y, flag, ctx->block[9], ctx->block[11], hqx_quant_chroma);
+
+    return 0;
+}
+
+static int hqx_decode_444a(HQXContext *ctx, AVFrame *pic,
+                           GetBitContext *gb, int x, int y)
+{
+    const int *quants;
+    int flag = 0;
+    int last_dc;
+    int i, ret;
+    int cbp;
+
+    cbp = get_vlc2(gb, ctx->cbp_vlc.table, ctx->cbp_vlc.bits, 1);
+
+    for (i = 0; i < 16; i++)
+        memset(ctx->block[i], 0, sizeof(**ctx->block) * 64);
+    for (i = 0; i < 16; i++)
+        ctx->block[i][0] = -0x800;
+    if (cbp) {
+        if (ctx->interlaced)
+            flag = get_bits1(gb);
+
+        quants = hqx_quants[get_bits(gb, 4)];
+
+        cbp |= cbp << 4; // alpha CBP
+        cbp |= cbp << 8; // chroma CBP
+        for (i = 0; i < 16; i++) {
+            if (i == 0 || i == 4 || i == 8 || i == 12)
+                last_dc = 0;
+            if (cbp & (1 << i)) {
+                int vlc_index = ctx->dcb - 9;
+                ret = decode_block(gb, &ctx->dc_vlc[vlc_index], quants,
+                                   ctx->dcb, ctx->block[i], &last_dc);
+                if (ret < 0)
+                    return ret;
+            }
+        }
+    }
+
+    put_blocks(pic, 3, x,     y, flag, ctx->block[ 0], ctx->block[ 2], hqx_quant_luma);
+    put_blocks(pic, 3, x + 8, y, flag, ctx->block[ 1], ctx->block[ 3], hqx_quant_luma);
+    put_blocks(pic, 0, x,     y, flag, ctx->block[ 4], ctx->block[ 6], hqx_quant_luma);
+    put_blocks(pic, 0, x + 8, y, flag, ctx->block[ 5], ctx->block[ 7], hqx_quant_luma);
+    put_blocks(pic, 2, x,     y, flag, ctx->block[ 8], ctx->block[10], hqx_quant_chroma);
+    put_blocks(pic, 2, x + 8, y, flag, ctx->block[ 9], ctx->block[11], hqx_quant_chroma);
+    put_blocks(pic, 1, x,     y, flag, ctx->block[12], ctx->block[14], hqx_quant_chroma);
+    put_blocks(pic, 1, x + 8, y, flag, ctx->block[13], ctx->block[15], hqx_quant_chroma);
+
+    return 0;
+}
+
+static const int shuffle_16[16] = {
+    0, 5, 11, 14, 2, 7, 9, 13, 1, 4, 10, 15, 3, 6, 8, 12
+};
+
+static int decode_slice(HQXContext *ctx, AVFrame *pic, GetBitContext *gb,
+                        int slice_no, mb_decode_func decode_func)
+{
+    int mb_w = (ctx->width  + 15) >> 4;
+    int mb_h = (ctx->height + 15) >> 4;
+    int grp_w = (mb_w + 4) / 5;
+    int grp_h = (mb_h + 4) / 5;
+    int grp_h_edge = grp_w * (mb_w / grp_w);
+    int grp_v_edge = grp_h * (mb_h / grp_h);
+    int grp_v_rest = mb_w - grp_h_edge;
+    int grp_h_rest = mb_h - grp_v_edge;
+    int num_mbs = mb_w * mb_h;
+    int num_tiles = (num_mbs + 479) / 480;
+    int std_tile_blocks = num_mbs / (16 * num_tiles);
+    int g_tile = slice_no * num_tiles;
+    int blk_addr, loc_addr, mb_x, mb_y, pos, loc_row, i;
+    int tile_blocks, tile_limit, tile_no;
+
+    for (tile_no = 0; tile_no < num_tiles; tile_no++, g_tile++) {
+        tile_blocks = std_tile_blocks;
+        tile_limit = -1;
+        if (g_tile < num_mbs - std_tile_blocks * 16 * num_tiles) {
+            tile_limit = num_mbs / (16 * num_tiles);
+            tile_blocks++;
+        }
+        for (i = 0; i < tile_blocks; i++) {
+            if (i == tile_limit)
+                blk_addr = g_tile + 16 * num_tiles * i;
+            else
+                blk_addr = tile_no + 16 * num_tiles * i +
+                           num_tiles * shuffle_16[(i + slice_no) & 0xF];
+            loc_row  = grp_h * (blk_addr / (grp_h * mb_w));
+            loc_addr =          blk_addr % (grp_h * mb_w);
+            if (loc_row >= grp_v_edge) {
+                mb_x = grp_w * (loc_addr / (grp_h_rest * grp_w));
+                pos  =          loc_addr % (grp_h_rest * grp_w);
+            } else {
+                mb_x = grp_w * (loc_addr / (grp_h * grp_w));
+                pos  =          loc_addr % (grp_h * grp_w);
+            }
+            if (mb_x >= grp_h_edge) {
+                mb_x +=            pos % grp_v_rest;
+                mb_y  = loc_row + (pos / grp_v_rest);
+            } else {
+                mb_x +=            pos % grp_w;
+                mb_y  = loc_row + (pos / grp_w);
+            }
+            decode_func(ctx, pic, gb, mb_x * 16, mb_y * 16);
+        }
+    }
+
+    return 0;
+}
+
+static int hqx_decode_frame(AVCodecContext *avctx, void *data,
+                            int *got_picture_ptr, AVPacket *avpkt)
+{
+    HQXContext *ctx = avctx->priv_data;
+    AVFrame *pic = data;
+    uint8_t *src = avpkt->data;
+    uint32_t info_tag, info_offset;
+    int data_start;
+    unsigned data_size;
+    GetBitContext gb;
+    int i, ret;
+    int slice;
+    uint32_t slice_off[17];
+    mb_decode_func decode_func = 0;
+
+    if (avpkt->size < 8)
+        return AVERROR_INVALIDDATA;
+
+    /* Skip the INFO header if present */
+    info_offset = 0;
+    info_tag    = AV_RL32(src);
+    if (info_tag == MKTAG('I', 'N', 'F', 'O')) {
+        info_offset = AV_RL32(src + 4);
+        if (info_offset > UINT32_MAX - 8 || info_offset + 8 > avpkt->size) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Invalid INFO header offset: 0x%08"PRIX32" is too large.\n",
+                   info_offset);
+            return AVERROR_INVALIDDATA;
+        }
+
+        info_offset += 8;
+        src         += info_offset;
+
+        av_log(avctx, AV_LOG_DEBUG, "Skipping INFO chunk.\n");
+    }
+
+    data_start = src - avpkt->data;
+    data_size  = avpkt->size - data_start;
+
+    if (data_size < HQX_HEADER_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "Frame too small.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (src[0] != 'H' || src[1] != 'Q') {
+        av_log(avctx, AV_LOG_ERROR, "Not an HQX frame.\n");
+        return AVERROR_INVALIDDATA;
+    }
+    ctx->interlaced = !(src[2] & 0x80);
+    ctx->format     = src[2] & 7;
+    ctx->dcb        = (src[3] & 3) + 8;
+    ctx->width      = AV_RB16(src + 4);
+    ctx->height     = AV_RB16(src + 6);
+    for (i = 0; i < 17; i++)
+        slice_off[i] = AV_RB24(src + 8 + i * 3);
+
+    if (ctx->dcb == 8) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid DC precision %d.\n", ctx->dcb);
+        return AVERROR_INVALIDDATA;
+    }
+    ret = av_image_check_size(ctx->width, ctx->height, 0, avctx);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid stored dimenstions %dx%d.\n",
+               ctx->width, ctx->height);
+        return AVERROR_INVALIDDATA;
+    }
+
+    avctx->coded_width         = FFALIGN(ctx->width,  16);
+    avctx->coded_height        = FFALIGN(ctx->height, 16);
+    avctx->width               = ctx->width;
+    avctx->height              = ctx->height;
+    avctx->bits_per_raw_sample = 10;
+
+    switch (ctx->format) {
+    case HQX_422:
+        avctx->pix_fmt = AV_PIX_FMT_YUV422P16;
+        decode_func = hqx_decode_422;
+        break;
+    case HQX_444:
+        avctx->pix_fmt = AV_PIX_FMT_YUV444P16;
+        decode_func = hqx_decode_444;
+        break;
+    case HQX_422A:
+        avctx->pix_fmt = AV_PIX_FMT_YUVA422P16;
+        decode_func = hqx_decode_422a;
+        break;
+    case HQX_444A:
+        avctx->pix_fmt = AV_PIX_FMT_YUVA444P16;
+        decode_func = hqx_decode_444a;
+        break;
+    }
+    if (!decode_func) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid format: %d.\n", ctx->format);
+        return AVERROR_INVALIDDATA;
+    }
+
+    ret = ff_get_buffer(avctx, pic, 0);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
+        return ret;
+    }
+
+    for (slice = 0; slice < 16; slice++) {
+        if (slice_off[slice] < HQX_HEADER_SIZE ||
+            slice_off[slice] >= slice_off[slice + 1] ||
+            slice_off[slice + 1] > data_size) {
+            av_log(avctx, AV_LOG_ERROR, "Invalid slice size.\n");
+            break;
+        }
+        ret = init_get_bits(&gb, src + slice_off[slice],
+                            (slice_off[slice + 1] - slice_off[slice]) * 8);
+        if (ret < 0)
+            return ret;
+        ret = decode_slice(ctx, pic, &gb, slice, decode_func);
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "Error decoding slice %d.\n", slice);
+        }
+    }
+
+    pic->key_frame = 1;
+    pic->pict_type = AV_PICTURE_TYPE_I;
+
+    *got_picture_ptr = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int hqx_decode_close(AVCodecContext *avctx)
+{
+    int i;
+    HQXContext *ctx = avctx->priv_data;
+
+    ff_free_vlc(&ctx->cbp_vlc);
+    for (i = 0; i < 3; i++) {
+        ff_free_vlc(&ctx->dc_vlc[i]);
+    }
+
+    return 0;
+}
+
+static av_cold int hqx_decode_init(AVCodecContext *avctx)
+{
+    HQXContext *ctx = avctx->priv_data;
+    int ret = ff_hqx_init_vlcs(ctx);
+    if (ret < 0)
+        hqx_decode_close(avctx);
+    return ret;
+}
+
+AVCodec ff_hqx_decoder = {
+    .name           = "hqx",
+    .long_name      = NULL_IF_CONFIG_SMALL("Canopus HQX"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_HQX,
+    .priv_data_size = sizeof(HQXContext),
+    .init           = hqx_decode_init,
+    .decode         = hqx_decode_frame,
+    .close          = hqx_decode_close,
+    .capabilities   = CODEC_CAP_DR1,
+};