[FFmpeg-devel] [PATCH v8 1/3] libavcodec/jpeg2000dec.c: Split function and modify structs for PPM marker support

[gautamramk at gmail.com]

From: Gautam Ramakrishnan <gautamramk at gmail.com>

---
 libavcodec/jpeg2000dec.c | 48 ++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 7103cd6ceb..9d52969821 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;
@@ -935,21 +939,32 @@ static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
     int bandno, cblkno, ret, nb_code_blocks;
     int cwsno;
 
+// This part decodes the packet header
+
     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 appropriate 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);
+        // Save state of stream
+        if (tile->has_ppt)
+            tile->packed_headers_stream = s->g;
+        else
+            tile->tile_part[*tp_index].tpg = s->g;
         return 0;
     } else if (ret < 0)
         return ret;
@@ -1056,6 +1071,23 @@ 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));
     }
 
+    if (tile->has_ppt)
+        tile->packed_headers_stream = s->g;
+    else
+        tile->tile_part[*tp_index].tpg = s->g;
+
+// This part decodes the packet data.
+    // Select appropriate stream to read from
+    s->g = tile->tile_part[*tp_index].tpg;
+    if (tile->has_ppt) {
+        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 +1129,8 @@ 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;
 }
 
-- 
2.17.1