diff options
| -rw-r--r-- | libavcodec/jpegtables.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/libavcodec/jpegtables.c b/libavcodec/jpegtables.c index cbe5523cb4..fa5c6f9fc5 100644 --- a/libavcodec/jpegtables.c +++ b/libavcodec/jpegtables.c @@ -130,14 +130,25 @@ void ff_mjpeg_build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, { int i, j, k,nb, code, sym; - code = 0; + /* Some badly encoded files [1] map 2 different codes to symbol 0. + Only the first one is valid, so we zero-initialize this here and + make sure we only set it once (the first time) in the loop below. + + [1]: Embedded JPEGs in "X7 RAW" and "X7 CinemaDNG" samples here: + https://www.dji.com/gr/zenmuse-x7/info#downloads + */ + huff_size[0] = 0; + k = 0; + code = 0; for(i=1;i<=16;i++) { nb = bits_table[i]; for(j=0;j<nb;j++) { sym = val_table[k++]; - huff_size[sym] = i; - huff_code[sym] = code; + if (sym != 0 || huff_size[sym] == 0) { /* see comment above */ + huff_size[sym] = i; + huff_code[sym] = code; + } code++; } code <<= 1; |