diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c index c7a87734e5..4ce49fd51c 100644 --- a/libavcodec/bitstream.c +++ b/libavcodec/bitstream.c @@ -132,6 +132,8 @@ static int alloc_table(VLC *vlc, int size, int use_static) return index; } +#define LOCALBUF_ELEMS 1500 // the maximum currently needed is 1296 by rv34 + typedef struct VLCcode { uint8_t bits; VLC_TYPE symbol; @@ -140,6 +142,31 @@ typedef struct VLCcode { uint32_t code; } VLCcode; +static int vlc_common_init(VLC *vlc_arg, int nb_bits, int nb_codes, + VLC **vlc, VLC *localvlc, VLCcode **buf, + int flags) +{ + *vlc = vlc_arg; + (*vlc)->bits = nb_bits; + if (flags & INIT_VLC_USE_NEW_STATIC) { + av_assert0(nb_codes <= LOCALBUF_ELEMS); + *localvlc = *vlc_arg; + *vlc = localvlc; + (*vlc)->table_size = 0; + } else { + (*vlc)->table = NULL; + (*vlc)->table_allocated = 0; + (*vlc)->table_size = 0; + } + if (nb_codes > LOCALBUF_ELEMS) { + *buf = av_malloc_array(nb_codes, sizeof(VLCcode)); + if (!*buf) + return AVERROR(ENOMEM); + } + + return 0; +} + static int compare_vlcspec(const void *a, const void *b) { const VLCcode *sa = a, *sb = b; @@ -248,6 +275,27 @@ static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, return table_index; } +static int vlc_common_end(VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes, + int flags, VLC *vlc_arg, VLCcode localbuf[LOCALBUF_ELEMS]) +{ + int ret = build_table(vlc, nb_bits, nb_codes, codes, flags); + + if (flags & INIT_VLC_USE_NEW_STATIC) { + if(vlc->table_size != vlc->table_allocated) + av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); + + av_assert0(ret >= 0); + *vlc_arg = *vlc; + } else { + if (codes != localbuf) + av_free(codes); + if (ret < 0) { + av_freep(&vlc->table); + return ret; + } + } + return 0; +} /* Build VLC decoding tables suitable for use with get_vlc(). @@ -278,30 +326,14 @@ int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes, const void *symbols, int symbols_wrap, int symbols_size, int flags) { - VLCcode *buf; + VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; int i, j, ret; - VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34 VLC localvlc, *vlc; - vlc = vlc_arg; - vlc->bits = nb_bits; - if (flags & INIT_VLC_USE_NEW_STATIC) { - av_assert0(nb_codes <= FF_ARRAY_ELEMS(localbuf)); - localvlc = *vlc_arg; - vlc = &localvlc; - vlc->table_size = 0; - } else { - vlc->table = NULL; - vlc->table_allocated = 0; - vlc->table_size = 0; - } - if (nb_codes > FF_ARRAY_ELEMS(localbuf)) { - buf = av_malloc_array(nb_codes, sizeof(VLCcode)); - if (!buf) - return AVERROR(ENOMEM); - } else - buf = localbuf; - + ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc, + &buf, flags); + if (ret < 0) + return ret; av_assert0(symbols_size <= 2 || !symbols); j = 0; @@ -342,25 +374,59 @@ int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes, COPY(len && len <= nb_bits); nb_codes = j; - ret = build_table(vlc, nb_bits, nb_codes, buf, flags); - - if (flags & INIT_VLC_USE_NEW_STATIC) { - if(vlc->table_size != vlc->table_allocated) - av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); - - av_assert0(ret >= 0); - *vlc_arg = *vlc; - } else { - if (buf != localbuf) - av_free(buf); - if (ret < 0) { - av_freep(&vlc->table); - return ret; - } - } - return 0; + return vlc_common_end(vlc, nb_bits, nb_codes, buf, + flags, vlc_arg, localbuf); } +int ff_init_vlc_from_lengths(VLC *vlc_arg, int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags, void *logctx) +{ + VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; + VLC localvlc, *vlc; + uint64_t code; + int ret, j, len_max = FFMIN(32, 3 * nb_bits); + + ret = vlc_common_init(vlc_arg, nb_bits, nb_codes, &vlc, &localvlc, + &buf, flags); + if (ret < 0) + return ret; + + j = code = 0; + for (int i = 0; i < nb_codes; i++, lens += lens_wrap) { + int len = *lens; + if (len > 0) { + unsigned sym; + + buf[j].bits = len; + if (symbols) + GET_DATA(sym, symbols, i, symbols_wrap, symbols_size) + else + sym = i; + buf[j].symbol = sym + offset; + buf[j++].code = code; + } else if (len < 0) { + len = -len; + } else + continue; + if (len > len_max || code & ((1U << (32 - len)) - 1)) { + av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len); + goto fail; + } + code += 1U << (32 - len); + if (code > UINT32_MAX + 1ULL) { + av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n"); + goto fail; + } + } + return vlc_common_end(vlc, nb_bits, j, buf, + flags, vlc_arg, localbuf); +fail: + if (buf != localbuf) + av_free(buf); + return AVERROR_INVALIDDATA; +} void ff_free_vlc(VLC *vlc) { diff --git a/libavcodec/vlc.h b/libavcodec/vlc.h index 22d3e33485..50a1834b84 100644 --- a/libavcodec/vlc.h +++ b/libavcodec/vlc.h @@ -49,6 +49,41 @@ int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags); + +/** + * Build VLC decoding tables suitable for use with get_vlc2() + * + * This function takes lengths and symbols and calculates the codes from them. + * For this the input lengths and symbols have to be sorted according to "left + * nodes in the corresponding tree first". + * + * @param[in,out] vlc The VLC to be initialized; table and table_allocated + * must have been set when initializing a static VLC, + * otherwise this will be treated as uninitialized. + * @param[in] nb_bits The number of bits to use for the VLC table; + * higher values take up more memory and cache, but + * allow to read codes with fewer reads. + * @param[in] nb_codes The number of provided length and (if supplied) symbol + * entries. + * @param[in] lens The lengths of the codes. Entries > 0 correspond to + * valid codes; entries == 0 will be skipped and entries + * with len < 0 indicate that the tree is incomplete and + * has an open end of length -len at this position. + * @param[in] lens_wrap Stride (in bytes) of the lengths. + * @param[in] symbols The symbols, i.e. what is returned from get_vlc2() + * when the corresponding code is encountered. + * May be NULL, then 0, 1, 2, 3, 4,... will be used. + * @param[in] symbols_wrap Stride (in bytes) of the symbols. + * @param[in] symbols_size Size of the symbols. 1 and 2 are supported. + * @param[in] offset An offset to apply to all the valid symbols. + * @param[in] flags A combination of the INIT_VLC_* flags; notice that + * INIT_VLC_INPUT_LE is pointless and ignored. + */ +int ff_init_vlc_from_lengths(VLC *vlc, int nb_bits, int nb_codes, + const int8_t *lens, int lens_wrap, + const void *symbols, int symbols_wrap, int symbols_size, + int offset, int flags, void *logctx); + void ff_free_vlc(VLC *vlc); /* If INIT_VLC_INPUT_LE is set, the LSB bit of the codes used to @@ -87,4 +122,17 @@ void ff_free_vlc(VLC *vlc); #define INIT_LE_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \ INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size) +#define INIT_VLC_STATIC_FROM_LENGTHS(vlc, bits, nb_codes, lens, len_wrap, \ + symbols, symbols_wrap, symbols_size, \ + offset, flags, static_size) \ + do { \ + static VLC_TYPE table[static_size][2]; \ + (vlc)->table = table; \ + (vlc)->table_allocated = static_size; \ + ff_init_vlc_from_lengths(vlc, bits, nb_codes, lens, len_wrap, \ + symbols, symbols_wrap, symbols_size, \ + offset, flags | INIT_VLC_USE_NEW_STATIC, \ + NULL); \ + } while (0) + #endif /* AVCODEC_VLC_H */