[FFmpeg-devel] [PATCH 001/114] avcodec/bitstream: Add second function to create VLCs

[Andreas Rheinhardt]

Anton Khirnov:
> Quoting Andreas Rheinhardt (2020-11-10 11:46:58)
>> +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)
>> +{
>> +    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(NULL, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len);
> 
> Can you use a proper logging context here?
> 
Yes. This will of course mean that I will have to go with the flag in
patch four.

- Andreas