avcodec: add YUY2 Lossless Codec decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 472 insertions, 0 deletions

diff --git a/libavcodec/ylc.c b/libavcodec/ylc.c
new file mode 100644
index 0000000000..95a5e05baa
--- /dev/null
+++ b/libavcodec/ylc.c
@@ -0,0 +1,472 @@
+/*
+ * YUY2 Lossless Codec
+ *
+ * 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
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libavutil/imgutils.h"
+#include "libavutil/internal.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/mem.h"
+#include "avcodec.h"
+#include "bswapdsp.h"
+#include "get_bits.h"
+#include "huffyuvdsp.h"
+#include "internal.h"
+#include "unary.h"
+
+typedef struct YLCContext {
+    VLC vlc[4];
+    uint32_t table[1024];
+    uint8_t *table_bits;
+    uint8_t *bitstream_bits;
+    int table_bits_size;
+    int bitstream_bits_size;
+    BswapDSPContext bdsp;
+} YLCContext;
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    YLCContext *s = avctx->priv_data;
+
+    avctx->pix_fmt = AV_PIX_FMT_YUYV422;
+    ff_bswapdsp_init(&s->bdsp);
+
+    return 0;
+}
+
+typedef struct Node {
+    int16_t  sym;
+    int16_t  n0;
+    uint32_t count;
+    int16_t  l, r;
+} Node;
+
+static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
+                           Node *nodes, int node,
+                           uint32_t pfx, int pl, int *pos)
+{
+    int s;
+
+    s = nodes[node].sym;
+    if (s != -1) {
+        bits[*pos] = (~pfx) & ((1 << FFMAX(pl, 1)) - 1);
+        lens[*pos] = FFMAX(pl, 1);
+        xlat[*pos] = s + (pl == 0);
+        (*pos)++;
+    } else {
+        pfx <<= 1;
+        pl++;
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].l, pfx, pl,
+                       pos);
+        pfx |= 1;
+        get_tree_codes(bits, lens, xlat, nodes, nodes[node].r, pfx, pl,
+                       pos);
+    }
+}
+
+static int build_vlc(AVCodecContext *avctx, VLC *vlc, const uint32_t *table)
+{
+    Node nodes[512];
+    uint32_t bits[256];
+    int16_t lens[256];
+    uint8_t xlat[256];
+    int cur_node, i, j, pos = 0;
+
+    ff_free_vlc(vlc);
+
+    for (i = 0; i < 256; i++) {
+        nodes[i].count = table[i];
+        nodes[i].sym   = i;
+        nodes[i].n0    = -2;
+        nodes[i].l     = i;
+        nodes[i].r     = i;
+    }
+
+    cur_node = 256;
+    j = 0;
+    do {
+        for (i = 0; ; i++) {
+            int new_node = j;
+            int first_node = cur_node;
+            int second_node = cur_node;
+            int nd, st;
+
+            nodes[cur_node].count = -1;
+
+            do {
+                int val = nodes[new_node].count;
+                if (val && (val < nodes[first_node].count)) {
+                    if (val >= nodes[second_node].count) {
+                        first_node = new_node;
+                    } else {
+                        first_node = second_node;
+                        second_node = new_node;
+                    }
+                }
+                new_node += 1;
+            } while (new_node != cur_node);
+
+            if (first_node == cur_node)
+                break;
+
+            nd = nodes[second_node].count;
+            st = nodes[first_node].count;
+            nodes[second_node].count = 0;
+            nodes[first_node].count  = 0;
+            nodes[cur_node].count = nd + st;
+            nodes[cur_node].sym = -1;
+            nodes[cur_node].n0 = cur_node;
+            nodes[cur_node].l = first_node;
+            nodes[cur_node].r = second_node;
+            cur_node++;
+        }
+        j++;
+    } while (cur_node - 256 == j);
+
+    get_tree_codes(bits, lens, xlat, nodes, cur_node - 1, 0, 0, &pos);
+
+    return ff_init_vlc_sparse(vlc, 10, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
+}
+
+static const uint8_t table_y1[] = {
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
+    0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
+    0x02, 0x00,
+};
+
+static const uint8_t table_u[] = {
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x00,
+};
+
+static const uint8_t table_y2[] = {
+    0xFC, 0xFC, 0xFC, 0xFD, 0xFD, 0xFD, 0xFE, 0xFE,
+    0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0xFC,
+    0xFC, 0xFC, 0xFD, 0xFD, 0xFD, 0xFE, 0xFE, 0xFE,
+    0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0xFC, 0xFC,
+    0xFC, 0xFD, 0xFD, 0xFD, 0xFE, 0xFE, 0xFE, 0xFF,
+    0xFF, 0xFF, 0x00, 0x00, 0x00, 0xFD, 0xFD, 0xFD,
+    0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00,
+    0x00, 0x01, 0x01, 0x01, 0xFD, 0xFD, 0xFD, 0xFE,
+    0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00,
+    0x01, 0x01, 0x01, 0xFD, 0xFD, 0xFD, 0xFE, 0xFE,
+    0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x01,
+    0x01, 0x01, 0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF,
+    0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x02, 0x02,
+    0x02, 0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0x00,
+    0x00, 0x00, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02,
+    0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00,
+    0x00, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02, 0xFF,
+    0xFF, 0xFF, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01,
+    0x02, 0x02, 0x02, 0x03, 0x03, 0x03, 0xFF, 0xFF,
+    0xFF, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x02,
+    0x02, 0x02, 0x03, 0x03, 0x03, 0xFF, 0xFF, 0xFF,
+    0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x02, 0x02,
+    0x02, 0x03, 0x03, 0x03, 0x00, 0x00, 0x00, 0x01,
+    0x01, 0x01, 0x02, 0x02, 0x02, 0x03, 0x03, 0x03,
+    0x04, 0x04, 0x04, 0x00, 0x00, 0x00, 0x01, 0x01,
+    0x01, 0x02, 0x02, 0x02, 0x03, 0x03, 0x03, 0x04,
+    0x04, 0x04, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01,
+    0x02, 0x02, 0x02, 0x03, 0x03, 0x03, 0x04, 0x04,
+    0x04, 0x00,
+};
+
+static const uint8_t table_v[] = {
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF,
+    0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01,
+    0xFF, 0x00, 0x01, 0xFF, 0x00, 0x01, 0xFF, 0x00,
+    0x01, 0x00,
+};
+
+static int decode_frame(AVCodecContext *avctx,
+                        void *data, int *got_frame,
+                        AVPacket *avpkt)
+{
+    int TL[4] = { 128, 128, 128, 128 };
+    int L[4]  = { 128, 128, 128, 128 };
+    YLCContext *s = avctx->priv_data;
+    const uint8_t *buf = avpkt->data;
+    int ret, x, y, toffset, boffset;
+    AVFrame * const p = data;
+    GetBitContext gb;
+    uint8_t *dst;
+
+    if (avpkt->size <= 16)
+        return AVERROR_INVALIDDATA;
+
+    if (AV_RL32(buf) != MKTAG('Y', 'L', 'C', '0') ||
+        AV_RL32(buf + 4) != 0)
+        return AVERROR_INVALIDDATA;
+
+    toffset = AV_RL32(buf + 8);
+    if (toffset < 16 || toffset >= avpkt->size)
+        return AVERROR_INVALIDDATA;
+
+    boffset = AV_RL32(buf + 12);
+    if (toffset >= boffset || boffset >= avpkt->size)
+        return AVERROR_INVALIDDATA;
+
+    if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
+        return ret;
+
+    av_fast_malloc(&s->table_bits, &s->table_bits_size,
+                   boffset - toffset + AV_INPUT_BUFFER_PADDING_SIZE);
+    if (!s->table_bits)
+        return AVERROR(ENOMEM);
+
+    memcpy(s->table_bits, avpkt->data + toffset, boffset - toffset);
+    memset(s->table_bits + boffset - toffset, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+    s->bdsp.bswap_buf((uint32_t *) s->table_bits,
+                      (uint32_t *) s->table_bits,
+                      (boffset - toffset + 3) >> 2);
+    if ((ret = init_get_bits8(&gb, s->table_bits, boffset - toffset)) < 0)
+        return ret;
+
+    for (x = 0; x < 1024; x++) {
+        unsigned len = get_unary(&gb, 1, 31);
+        uint32_t val = ((1U << len) - 1) + get_bits_long(&gb, len);
+
+        s->table[x] = val;
+    }
+
+    ret = build_vlc(avctx, &s->vlc[0], &s->table[0  ]);
+    if (ret < 0)
+        return ret;
+    ret = build_vlc(avctx, &s->vlc[1], &s->table[256]);
+    if (ret < 0)
+        return ret;
+    ret = build_vlc(avctx, &s->vlc[2], &s->table[512]);
+    if (ret < 0)
+        return ret;
+    ret = build_vlc(avctx, &s->vlc[3], &s->table[768]);
+    if (ret < 0)
+        return ret;
+
+    av_fast_malloc(&s->bitstream_bits, &s->bitstream_bits_size,
+                   avpkt->size - boffset + AV_INPUT_BUFFER_PADDING_SIZE);
+    if (!s->bitstream_bits)
+        return AVERROR(ENOMEM);
+
+    memcpy(s->bitstream_bits, avpkt->data + boffset, avpkt->size - boffset);
+    memset(s->bitstream_bits + avpkt->size - boffset, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+    s->bdsp.bswap_buf((uint32_t *) s->bitstream_bits,
+                      (uint32_t *) s->bitstream_bits,
+                      (avpkt->size - boffset) >> 2);
+    if ((ret = init_get_bits8(&gb, s->bitstream_bits, avpkt->size - boffset)) < 0)
+        return ret;
+
+    dst = p->data[0];
+    for (y = 0; y < avctx->height; y++) {
+        memset(dst, 0, avctx->width * 2);
+        dst += p->linesize[0];
+    }
+
+    dst = p->data[0];
+    for (y = 0; y < avctx->height; y++) {
+        for (x = 0; x < avctx->width * 2 && y < avctx->height;) {
+            if (get_bits_left(&gb) <= 0)
+                return AVERROR_INVALIDDATA;
+
+            if (get_bits1(&gb)) {
+                int val = get_vlc2(&gb, s->vlc[0].table, s->vlc[0].bits, 3);
+                if (val < 0) {
+                    return AVERROR_INVALIDDATA;
+                } else if (val < 0xE1) {
+                    dst[x    ] = table_y1[val];
+                    dst[x + 1] = table_u[val];
+                    dst[x + 2] = table_y2[val];
+                    dst[x + 3] = table_v[val];
+                    x += 4;
+                } else {
+                    int incr = (val - 0xDF) * 4;
+                    if (x + incr >= avctx->width * 2) {
+                        int iy = ((x + incr) / (avctx->width * 2));
+                        x  = (x + incr) % (avctx->width * 2);
+                        y += iy;
+                        dst += iy * p->linesize[0];
+                    } else {
+                        x += incr;
+                    }
+                }
+            } else {
+                int y1, y2, u, v;
+
+                y1 = get_vlc2(&gb, s->vlc[1].table, s->vlc[1].bits, 3);
+                u  = get_vlc2(&gb, s->vlc[2].table, s->vlc[2].bits, 3);
+                y2 = get_vlc2(&gb, s->vlc[1].table, s->vlc[1].bits, 3);
+                v  = get_vlc2(&gb, s->vlc[3].table, s->vlc[3].bits, 3);
+                if (y1 < 0 || y2 < 0 || u < 0 || v < 0)
+                    return AVERROR_INVALIDDATA;
+                dst[x    ] = y1;
+                dst[x + 1] = u;
+                dst[x + 2] = y1 + y2;
+                dst[x + 3] = v;
+                x += 4;
+            }
+        }
+        dst += p->linesize[0];
+    }
+
+    dst = p->data[0];
+    for (x = 0; x < avctx->width * 2; x += 4) {
+        dst[x    ] =        dst[x    ] + L[0];
+        dst[x + 2] = L[0] = dst[x + 2] + L[0];
+        L[1] = dst[x + 1] + L[1];
+        dst[x + 1] = L[1];
+        L[2] = dst[x + 3] + L[2];
+        dst[x + 3] = L[2];
+    }
+    dst += p->linesize[0];
+
+    for (y = 1; y < avctx->height; y++) {
+        x = 0;
+        dst[x    ] =        dst[x    ] + L[0] + dst[x + 0 - p->linesize[0]] - TL[0];
+        dst[x + 2] = L[0] = dst[x + 2] + L[0] + dst[x + 2 - p->linesize[0]] - TL[0];
+        TL[0] = dst[x + 2 - p->linesize[0]];
+        L[1] = dst[x + 1] + L[1] + dst[x + 1 - p->linesize[0]] - TL[1];
+        dst[x + 1] = L[1];
+        TL[1] = dst[x + 1 - p->linesize[0]];
+        L[2] = dst[x + 3] + L[2] + dst[x + 3 - p->linesize[0]] - TL[2];
+        dst[x + 3] = L[2];
+        TL[2] = dst[x + 3 - p->linesize[0]];
+        for (x = 4; x < avctx->width * 2; x += 4) {
+            dst[x    ] =        dst[x    ] + L[0] + dst[x + 0 - p->linesize[0]] - TL[0];
+            dst[x + 2] = L[0] = dst[x + 2] + L[0] + dst[x + 2 - p->linesize[0]] - TL[0];
+            TL[0] = dst[x + 2 - p->linesize[0]];
+            L[1] = dst[x + 1] + L[1] + dst[x + 1 - p->linesize[0]] - TL[1];
+            dst[x + 1] = L[1];
+            TL[1] = dst[x + 1 - p->linesize[0]];
+            L[2] = dst[x + 3] + L[2] + dst[x + 3 - p->linesize[0]] - TL[2];
+            dst[x + 3] = L[2];
+            TL[2] = dst[x + 3 - p->linesize[0]];
+        }
+        dst += p->linesize[0];
+    }
+
+    p->pict_type = AV_PICTURE_TYPE_I;
+    p->key_frame = 1;
+    *got_frame   = 1;
+
+    return avpkt->size;
+}
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+    YLCContext *s = avctx->priv_data;
+
+    ff_free_vlc(&s->vlc[0]);
+    ff_free_vlc(&s->vlc[1]);
+    ff_free_vlc(&s->vlc[2]);
+    ff_free_vlc(&s->vlc[3]);
+
+    return 0;
+}
+
+AVCodec ff_ylc_decoder = {
+    .name           = "ylc",
+    .long_name      = NULL_IF_CONFIG_SMALL("YUY2 Lossless Codec"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_YLC,
+    .priv_data_size = sizeof(YLCContext),
+    .init           = decode_init,
+    .close          = decode_end,
+    .decode         = decode_frame,
+    .capabilities   = AV_CODEC_CAP_DR1,
+};