diff options
| -rw-r--r-- | libavcodec/utvideodec.c | 42 |
1 files changed, 23 insertions, 19 deletions
diff --git a/libavcodec/utvideodec.c b/libavcodec/utvideodec.c index 8b47c14d98..1b10b3bd06 100644 --- a/libavcodec/utvideodec.c +++ b/libavcodec/utvideodec.c @@ -40,10 +40,16 @@ #include "thread.h" #include "utvideo.h" -static int build_huff(const uint8_t *src, VLC *vlc, int *fsym, unsigned nb_elems) +typedef struct HuffEntry { + uint8_t len; + uint16_t sym; +} HuffEntry; + +static int build_huff(UtvideoContext *c, const uint8_t *src, VLC *vlc, + int *fsym, unsigned nb_elems) { int i; - uint32_t codes[1024]; + HuffEntry he[1024]; uint8_t bits[1024]; uint16_t codes_count[33] = { 0 }; @@ -64,23 +70,21 @@ static int build_huff(const uint8_t *src, VLC *vlc, int *fsym, unsigned nb_elems if (codes_count[0] == nb_elems) return AVERROR_INVALIDDATA; - for (unsigned i = 32, nb_codes = 0; i > 0; i--) { - uint16_t curr = codes_count[i]; // # of leafs of length i - codes_count[i] = nb_codes / 2; // # of non-leaf nodes on level i - nb_codes = codes_count[i] + curr; // # of nodes on level i - } + /* For Ut Video, longer codes are to the left of the tree and + * for codes with the same length the symbol is descending from + * left to right. So after the next loop --codes_count[i] will + * be the index of the first (lowest) symbol of length i when + * indexed by the position in the tree with left nodes being first. */ + for (int i = 31; i >= 0; i--) + codes_count[i] += codes_count[i + 1]; + + for (unsigned i = 0; i < nb_elems; i++) + he[--codes_count[bits[i]]] = (HuffEntry) { bits[i], i }; - for (unsigned i = nb_elems; i-- > 0;) { - if (!bits[i]) { - codes[i] = 0; - continue; - } - codes[i] = codes_count[bits[i]]++; - } #define VLC_BITS 11 - return init_vlc(vlc, VLC_BITS, nb_elems, - bits, sizeof(*bits), sizeof(*bits), - codes, sizeof(*codes), sizeof(*codes), 0); + return ff_init_vlc_from_lengths(vlc, VLC_BITS, codes_count[0], + &he[0].len, sizeof(*he), + &he[0].sym, sizeof(*he), 2, 0, 0, c->avctx); } static int decode_plane10(UtvideoContext *c, int plane_no, @@ -95,7 +99,7 @@ static int decode_plane10(UtvideoContext *c, int plane_no, GetBitContext gb; int prev, fsym; - if ((ret = build_huff(huff, &vlc, &fsym, 1024)) < 0) { + if ((ret = build_huff(c, huff, &vlc, &fsym, 1024)) < 0) { av_log(c->avctx, AV_LOG_ERROR, "Cannot build Huffman codes\n"); return ret; } @@ -255,7 +259,7 @@ static int decode_plane(UtvideoContext *c, int plane_no, return 0; } - if (build_huff(src, &vlc, &fsym, 256)) { + if (build_huff(c, src, &vlc, &fsym, 256)) { av_log(c->avctx, AV_LOG_ERROR, "Cannot build Huffman codes\n"); return AVERROR_INVALIDDATA; } |