[FFmpeg-devel,v10,1/3] libavcodec/jpeg2000dec.c: Add support for PPT marker

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 7103cd6ceb..02905b9e49 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -83,6 +83,10 @@  typedef struct Jpeg2000Tile {
     Jpeg2000QuantStyle  qntsty[4];
     Jpeg2000POC         poc;
     Jpeg2000TilePart    tile_part[32];
+    uint8_t             has_ppt;                // whether this tile has a ppt marker
+    uint8_t             *packed_headers;        // contains packed headers. Used only along with PPT marker
+    int                 packed_headers_size;    // size in bytes of the packed headers
+    GetByteContext      packed_headers_stream;  // byte context corresponding to packed headers
     uint16_t tp_idx;                    // Tile-part index
     int coord[2][2];                    // border coordinates {{x0, x1}, {y0, y1}}
 } Jpeg2000Tile;
@@ -855,6 +859,39 @@  static int get_plt(Jpeg2000DecoderContext *s, int n)
     return 0;
 }
 
+static int get_ppt(Jpeg2000DecoderContext *s, int n)
+{
+    Jpeg2000Tile *tile;
+
+    if (s->curtileno < 0)
+        return AVERROR_INVALIDDATA;
+
+    tile = &s->tile[s->curtileno];
+    if (tile->tp_idx != 0) {
+        av_log(s->avctx, AV_LOG_ERROR,
+               "PPT marker can occur only on first tile part of a tile.\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    tile->has_ppt = 1;  // this tile has a ppt marker
+/*    Zppt = */ bytestream2_get_byte(&s->g); // Zppt is skipped and not used
+    if (!tile->packed_headers) {
+        tile->packed_headers = av_malloc_array(n - 3, 1);
+        memcpy(tile->packed_headers, s->g.buffer, n - 3);
+        tile->packed_headers_size = n - 3;
+    } else {
+        tile->packed_headers = av_realloc_array(tile->packed_headers,
+                                                tile->packed_headers_size + n - 3,
+                                                1);
+        memcpy(tile->packed_headers + tile->packed_headers_size,
+               s->g.buffer, n - 3);
+        tile->packed_headers_size += n - 3;
+    }
+    bytestream2_skip(&s->g, n - 3);
+
+    return 0;
+}
+
 static int init_tile(Jpeg2000DecoderContext *s, int tileno)
 {
     int compno;
@@ -938,19 +975,23 @@  static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
     if (layno < rlevel->band[0].prec[precno].decoded_layers)
         return 0;
     rlevel->band[0].prec[precno].decoded_layers = layno + 1;
-
-    if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
-        if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
-            s->g = tile->tile_part[++(*tp_index)].tpg;
+    // Select stream to read from
+    if (tile->has_ppt) {
+        s->g = tile->packed_headers_stream;
+    } else {
+        s->g = tile->tile_part[*tp_index].tpg;
+        if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
+            if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
+                s->g = tile->tile_part[++(*tp_index)].tpg;
+            }
         }
+        if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
+            bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
     }
 
-    if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
-        bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
-
     if (!(ret = get_bits(s, 1))) {
         jpeg2000_flush(s);
-        return 0;
+        goto skip_data;
     } else if (ret < 0)
         return ret;
 
@@ -1056,6 +1097,18 @@  static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
             av_log(s->avctx, AV_LOG_ERROR, "EPH marker not found. instead %X\n", bytestream2_peek_be32(&s->g));
     }
 
+    // Save state of stream
+    if (tile->has_ppt) {
+        tile->packed_headers_stream = s->g;
+        s->g = tile->tile_part[*tp_index].tpg;
+        if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
+            if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
+                s->g = tile->tile_part[++(*tp_index)].tpg;
+            }
+        }
+        if (bytestream2_peek_be32(&s->g) == JPEG2000_SOP_FIXED_BYTES)
+            bytestream2_skip(&s->g, JPEG2000_SOP_BYTE_LENGTH);
+    }
     for (bandno = 0; bandno < rlevel->nbands; bandno++) {
         Jpeg2000Band *band = rlevel->band + bandno;
         Jpeg2000Prec *prec = band->prec + precno;
@@ -1097,6 +1150,15 @@  static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
             av_freep(&cblk->lengthinc);
         }
     }
+    // Save state of stream
+    tile->tile_part[*tp_index].tpg = s->g;
+    return 0;
+
+skip_data:
+    if (tile->has_ppt)
+        tile->packed_headers_stream = s->g;
+    else
+        tile->tile_part[*tp_index].tpg = s->g;
     return 0;
 }
 
@@ -1929,6 +1991,11 @@  static int jpeg2000_read_main_headers(Jpeg2000DecoderContext *s)
                 av_log(s->avctx, AV_LOG_ERROR, "Invalid tpend\n");
                 return AVERROR_INVALIDDATA;
             }
+
+            if (tile->has_ppt && tile->tp_idx == 0) {
+                bytestream2_init(&tile->packed_headers_stream, tile->packed_headers, tile->packed_headers_size);
+            }
+
             bytestream2_init(&tp->tpg, s->g.buffer, tp->tp_end - s->g.buffer);
             bytestream2_skip(&s->g, tp->tp_end - s->g.buffer);
 
@@ -1991,6 +2058,10 @@  static int jpeg2000_read_main_headers(Jpeg2000DecoderContext *s)
             // Packet length, tile-part header
             ret = get_plt(s, len);
             break;
+        case JPEG2000_PPT:
+            // Packed headers, tile-part header
+            ret = get_ppt(s, len);
+            break;
         default:
             av_log(s->avctx, AV_LOG_ERROR,
                    "unsupported marker 0x%.4"PRIX16" at pos 0x%X\n",
@@ -2020,7 +2091,6 @@  static int jpeg2000_read_bitstream_packets(Jpeg2000DecoderContext *s)
         if ((ret = init_tile(s, tileno)) < 0)
             return ret;
 
-        s->g = tile->tile_part[0].tpg;
         if ((ret = jpeg2000_decode_packets(s, tile)) < 0)
             return ret;
     }