diff options
Diffstat (limited to 'libavcodec/mjpegdec.c')
| -rw-r--r-- | libavcodec/mjpegdec.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index e7a4e08c1c..44bbae010c 100644 --- a/libavcodec/mjpegdec.c +++ b/libavcodec/mjpegdec.c @@ -50,6 +50,21 @@ #include "bytestream.h" +static void build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, + const uint8_t *bits_table) +{ + for (int i = 1, code = 0, k = 0; i <= 16; i++) { + int nb = bits_table[i]; + for (int j = 0; j < nb;j++) { + huff_size[k] = i; + huff_code[k] = code; + code++; + k++; + } + code <<= 1; + } +} + static int build_vlc(VLC *vlc, const uint8_t *bits_table, const uint8_t *val_table, int nb_codes, int use_static, int is_ac) @@ -61,13 +76,14 @@ static int build_vlc(VLC *vlc, const uint8_t *bits_table, av_assert0(nb_codes <= 256); - ff_mjpeg_build_huffman_codes(huff_size, huff_code, bits_table, val_table); + build_huffman_codes(huff_size, huff_code, bits_table); - for (i = 0; i < 256; i++) - huff_sym[i] = i + 16 * is_ac; + for (i = 0; i < 256; i++) { + huff_sym[i] = val_table[i] + 16 * is_ac; - if (is_ac) - huff_sym[0] = 16 * 256; + if (is_ac && !val_table[i]) + huff_sym[i] = 16 * 256; + } return ff_init_vlc_sparse(vlc, 9, nb_codes, huff_size, 1, 1, huff_code, 2, 2, huff_sym, 2, 2, use_static); @@ -240,7 +256,7 @@ int ff_mjpeg_decode_dqt(MJpegDecodeContext *s) /* decode huffman tables and build VLC decoders */ int ff_mjpeg_decode_dht(MJpegDecodeContext *s) { - int len, index, i, class, n, v, code_max; + int len, index, i, class, n, v; uint8_t bits_table[17]; uint8_t val_table[256]; int ret = 0; @@ -270,11 +286,8 @@ int ff_mjpeg_decode_dht(MJpegDecodeContext *s) if (len < n || n > 256) return AVERROR_INVALIDDATA; - code_max = 0; for (i = 0; i < n; i++) { v = get_bits(&s->gb, 8); - if (v > code_max) - code_max = v; val_table[i] = v; } len -= n; @@ -282,15 +295,15 @@ int ff_mjpeg_decode_dht(MJpegDecodeContext *s) /* build VLC and flush previous vlc if present */ ff_free_vlc(&s->vlcs[class][index]); av_log(s->avctx, AV_LOG_DEBUG, "class=%d index=%d nb_codes=%d\n", - class, index, code_max + 1); + class, index, n + 1); if ((ret = build_vlc(&s->vlcs[class][index], bits_table, val_table, - code_max + 1, 0, class > 0)) < 0) + n + 1, 0, class > 0)) < 0) return ret; if (class > 0) { ff_free_vlc(&s->vlcs[2][index]); if ((ret = build_vlc(&s->vlcs[2][index], bits_table, val_table, - code_max + 1, 0, 0)) < 0) + n + 1, 0, 0)) < 0) return ret; } |