static int replace_int_data_in_filename(char *buf, int buf_size, const char *filename, char placeholder, int64_t number)
{
    const char *p;
    char *q, buf1[20], c;
    int nd, len, addchar_count;
    int found_count = 0;

    q = buf;
    p = filename;
    for (;;) {
        c = *p;
        if (c == '\0')
            break;
        if (c == '%' && *(p+1) == '%')  // %%
            addchar_count = 2;
        else if (c == '%' && (av_isdigit(*(p+1)) || *(p+1) == placeholder)) {
            nd = 0;
            addchar_count = 1;
            while (av_isdigit(*(p + addchar_count))) {
                nd = nd * 10 + *(p + addchar_count) - '0';
                addchar_count++;
            }

            if (*(p + addchar_count) == placeholder) {
                len = snprintf(buf1, sizeof(buf1), "%0*"PRId64, (number < 0) ? nd : nd++, number);
                if (len < 1)  // returned error or empty buf1
                    goto fail;
                if ((q - buf + len) > buf_size - 1)
                    goto fail;
                memcpy(q, buf1, len);
                q += len;
                p += (addchar_count + 1);
                addchar_count = 0;
                found_count++;
            }

        } else
            addchar_count = 1;

        while (addchar_count--)
            if ((q - buf) < buf_size - 1)
                *q++ = *p++;
            else
                goto fail;
    }
    *q = '\0';
    return found_count;
fail:
    *q = '\0';
    return -1;
}